Harry said soft fruit goes off (10)
I believe the answer is:
disappears
'goes off' is the definition.
(I've seen this before)
'harry said soft fruit' is the wordplay.
'harry' indicates anagramming the letters (harry can mean to attack or spoil).
'soft' becomes 'p' (musical abbreviation for 'piano').
'fruit' becomes 'pears' (I've seen this before).
'said' with letters rearranged gives 'disa'.
'disa'+'p'+'pears'='DISAPPEARS'
(Other definitions for disappears that I've seen before include "goes missing" , "becomes lost" .)