Setter leaving bread to go off (3)
I believe the answer is:
rot
'go off' is the definition.
(I've seen this before)
'setter leaving bread' is the wordplay.
'setter' becomes 'I' (the person that set the crossword).
'leaving' is a deletion indicator.
'bread' becomes 'roti' (roti is a type of bread).
'roti' with 'i' removed is 'ROT'.
'to' is the link.
(Other definitions for rot that I've seen before include "Collapse" , "Cobblers" , "Drivel" , "Corruption" , "Rhubarb" .)