Question: Who did contestants have to perform for to get their next clue?
About the article "The Amazing Race 21", section "Leg 7 (Turkey → Russia)".

Candidate passages:
Once the Double Jeopardy!
round is concluded, the Final Jeopardy!
category is announced by the host, and a commercial break follows.
During the break, barriers are placed to separate each of the contestant lecterns from one another, and each contestant is asked to make one final wager (between $0 and their total score), writing it down on the electronic display using the light pen.
After the final commercial break, the Final Jeopardy!
clue is revealed and read by the host.
The contestants are given a time limit of thirty seconds to write their responses, again phrased in the form of a question.
During the time in which the contestants write their responses, the iconic "Think!"
music plays in the background.
Contestants who provide the correct response are awarded the values of their respective wagers.
Contestants who fail to provide the correct response, or to phrase their response in the form of a question (even if the response itself is correct), have that amount subtracted from their total scores.
During tournaments, if two or all three contestants are tied for first place with a positive score at the conclusion of the Final Jeopardy!
round, a one-clue tiebreaker round is played.
The tied contestants are presented with a category and the clue is then revealed.
The first contestant to ring in and provide the correct response becomes the champion and moves on to the next round of play.
Contestants are not eliminated from play for providing an incorrect response and are not allowed to win by default.
If a tournament game ends in a three-way tie for zero, all three contestants are eliminated, and the highest scoring of the remaining players advances to the next round as an additional wild card entrant. 
During the race, teams may face the following which may potentially slow them down:  U-Sving (U-Turn): It is located after a Detour where a team can force another trailing team to return and complete the other option of the Detour they did not select.
Veikryss (Intersection): It is where two teams compete to receive their next clue.
The team who wins the challenge will get their next clue while the losing team must then wait for another team to arrive to redo the challenge.
The cycle repeats until the last team left will have to, again, repeat the challenge.  
The team with the higher Big Sweep total (added with their sub total from bonuses and previous rounds) keeps their money and advances to the Super Sweep.
The team have 60 seconds to find the £2,000 prize (£5,000 in the revived version), by solving three clues.
The first clue is given by Dale and time doesn't start until the clue has been read.
The team must find the item from the clue to get the next clue.
The second clue leads the contestants to the final item, behind which the money is found.
As with the US version, the team has to find all three items and have their hands "on the money" before time expires.
If they don't, they only leave with the cash equivalent of the value of the goods in their trolley. 
A team of two contestants, always in the studio, had to use a library of (deliberately relevant) maps and reference materials to solve up to five clues, and communicate instructions via a radio link to a "skyrunner" who had the use of a helicopter.
The contestants were given the first clue for free, the solving of which would lead to the location of the second clue and so on until a trinket or other significant object was found by solving the final clue.
The contestants won a higher cash prize each time they solved a clue correctly.
This was all done "against the clock".
Even once the contestants had solved the final clue, the skyrunner still had to confirm they were correct, by reaching the final target.
On a few occasions, the contestants solved all five clues with time to spare, in which case, a bonus clue was given to the contestants.
This typically resulted in their winning a bottle of champagne.
One such occasion was the North Yorkshire episode (4.10), in which the bonus clue instructed them to go to "Great British Hospital X-ray Unit".
This was actually code for "return to the helicopter, registration G-BHXU", but Anneka alarmed the passers-by outside Skipton Castle by frantically asking "which way to the hospital?
"Understandably, the skyrunner and helicopter did not have freedom to fly and land anywhere they wished.
Although the pilot could to an extent request permission from airspace authorities to fly off-course, as happened on occasions, landings needed to be agreed in advance with landowners of a suitable location near the clue.
On occasions the helicopter would land in a clearly marked out area, especially at public places.
It is open to interpretation how much detail of the route was known in advance by either of the studio presenters or even the skyrunner herself, and hence to what extent the contestants were helped to correctly direct the skyrunner to the approximate location.
Kenneth Kendall has always stressed that he did not know the clues and locations in advance, and any help that he gave the contestants was from his own knowledge.
According to a "making of "Treasure Hunt"" programme, Anneka Rice was confined to the hotel on the day that the cameraman, video recordist and helicopter pilot undertook a rehearsal (typically the day before the programme was recorded), so she had no advance knowledge of the locations.
This did not stop her carrying out research about the general area in order to have a stock of interesting facts to fill in any awkward silences that might arise while the contestants were thinking. 
Air date: 4 May 2013  Colombo (Bandaranaike International Airport) to Singapore (Singapore Changi Airport)  Singapore (Bugis Junction – Fountain)  Singapore (Clarke Quay – G-MAX Reverse Bungy "or" Swissôtel The Stamford)  Singapore (Climb Asia Rock-climbing wall)  Singapore (Sentosa – MegaZip Adventure Park)  Singapore (Raffles Place – Postcard Stall)  Singapore (Chinese Garden – Bridge)  In this leg's Detour teams had to choose between ("Polit" – Flight) or ("Pokhid" – Walk).
In "Polit", teams had to ride the G-MAX Reverse Bungy.
While riding, teams needed to spot an umbrella lit with the race colours.
Once they locate the umbrella at a stall, they could get their next clue from the shopkeeper.
In Pokhid, teams needed to go to the Swissôtel The Stamford hotel and climb all 73 floors to the top to get their next clue.
In this leg's Roadblock, one team member needed to rock climb to get their next clue.
Additional tasks   At Bugis Junction, teams had to retrieve their next clue from a clue box surrounded by a dancing fountain.
At Sentosa, teams rode the MegaZip, a long zip-line.
After getting off the MegaZip, teams received their next clue.
Before proceeding to the postcard stall in Raffles Place, teams had to have their photograph taken with the Marina Bay Sands in the background.
If their photograph was satisfactory, they could choose a Postcard from the stall.
After having it stamped, they could proceeded to mail the postcard to Kiev in a nearby post box for their next clue.
After mailing it, a postman would give them their next clue.
After, teams had to search for their next clue.
What they needed to find out was that their next clue was printed on the flyers being distributed by locals in the vicinity.
The clue on the flyer pointed them to the Pit Stop, the bridge in the Chinese Garden.