### Clue: Book demonstrates what to do if a fault occurs (7)
### Answer: RESERVE 
 ### Explanation: Definition: Book,what to do if a fault occurs
 Double defn: 1st: As in "to book a restaurant table"; and 2nd: Re-serve/what a tennis, badminton, table-tennis player has to do if his/her first service is at fault/not in accordance with the rules of the game.