Hurried Federer finally hit an unreturnable serve (5)
I believe the answer is:
raced
'hurried' is the definition.
('race' can be a synonym of 'hurry')
'federer finally hit an unreturnable serve' is the wordplay.
'finally' says to take the final letters.
'hit' becomes 'ace' (acing is a kind of hitting).
'an unreturnable serve' becomes 'd' (I can't explain this - if you can you should believe this answer much more).
The last letter of 'federer' is 'r'.
'r'+'ace'+'d'='RACED'
Can you help me to learn more?
(Other definitions for raced that I've seen before include "Rushed" , "Ran fast" , "Cedar (anag)" , "Competed" , "Hurried" .)