Clue: Money deposited by the German road joining an autobahn? (6)
Answer: FEEDER
Explanation: Definition: road joining an autobahn
 FEE(money paid, in this case, deposited for the services of a professional) **plus**(by) DER(German for "the").
Defn: A road for traffic to join a highway, an example of which/? is the German autobahn.