I hear you, Mister Federer! (5)
I believe the answer is:
roger
'i hear you' is the definition.
(radio communications)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for roger that I've seen before include "Chap" , "Received (in radio comms)" , "Military 'OK'" , "Sir - de Coverley, English country dance" , "- - Moore (007)" .)