Said bananas and soft fruit go off (9)
I believe the answer is:
disappear
'go off' is the definition.
(I've seen this before)
'said bananas and soft fruit' is the wordplay.
'bananas' indicates anagramming the letters (informal term for mad).
'and' is a charade indicator (letters next to each other).
'soft' becomes 'p' (musical abbreviation for 'piano').
'fruit' becomes 'pear' (pear is a kind of fruit).
'said' anagrammed gives 'disa'.
'disa'+'p'+'pear'='DISAPPEAR'
(Other definitions for disappear that I've seen before include "Leave" , "Fly" , "Escape" , "Pass out of sight" , "Vanish from view" .)