Hated sending back produce (7)
I believe the answer is:
deliver
'produce' is the definition.
(I know that deliver is a kind of produce)
'hated sending back' is the wordplay.
'hated' becomes 'reviled' (both can mean detested).
'sending back' says the letters should be written in reverse.
'reviled' backwards is 'DELIVER'.
(Other definitions for deliver that I've seen before include "Free; supply" , "Hand over - release" , "Make a speech - free" , "Consign" , "Bring into the world - set free" .)