Love to classify fruit (6)
I believe the answer is:
orange
'fruit' is the definition.
(I know that orange is a type of fruit)
'love to classify' is the wordplay.
'love' becomes 'o' (love means zero in tennis).
'to classify' becomes 'range' (range can mean to rank or classify).
'o'+'range'='ORANGE'
(Other definitions for orange that I've seen before include "Go earn the fruit" , "Between red and yellow on the spectrum" , "Round fruit (6)" , "One's pipped" , "Onager (anag.)" .)