Longs, after exercise, for fruit (7)
I believe the answer is:
peaches
'for fruit' is the definition.
(peach is a type of fruit)
'longs after exercise' is the wordplay.
'longs' becomes 'aches' ('ache' can be a synonym of 'long').
'after' is a charade indicator (letters next to each other).
'exercise' becomes 'pe' (Physical Education).
'aches' after 'pe' is 'PEACHES'.
(Other definitions for peaches that I've seen before include "Make a speech about the fruit" , "Producing fine specimens" , "Juicy fruits" , "A speech (anag)" .)