Reach a trade-off about talk (4)
I believe the answer is:
chat
'talk' is the definition.
(chat can mean to talk)
'reach a trade-off about' is the wordplay.
'about' indicates the answer is hidden within the clue (the clue goes around or about the answer).
'CHAT' is hidden within 'reach a trade off'.
(Other definitions for chat that I've seen before include "Gossip" , "Communication" , "Friendly talk" , "Small songbird of the thrush family" , "waffle?" .)