The athlete has to have food (3)
I believe the answer is:
eat
'to have food' is the definition.
'the athlete has' is the wordplay.
'has' indicates the answer is hidden within the clue.
'EAT' is hidden in the letters of 'the athlete'.
(Other definitions for eat that I've seen before include "Partake of" , "Devour" , "tolerate in diet" , "Make food disappear" , "put away" .)