Athlete to drive off (5)
I believe the answer is:
diver
'athlete' is the definition.
(diver is a kind of athlete)
'drive off' is the wordplay.
'off' indicates anagramming the letters.
'drive' with letters rearranged gives 'DIVER'.
'to' is the link.
(Other definitions for diver that I've seen before include "Drive (anag.)" , "One plunges head first into water" , "Large waterbird" , "Cheating footballer" , "Bird that plunges" .)