The opposite of talk (8)
I believe the answer is:
converse
This clue is a double definition.
'the opposite' is the first definition.
(I've seen this before)
'talk' is the second definition.
(conversing is a kind of talking)
'of' is the link.
(Other definitions for converse that I've seen before include "Communicate with" , "Quite the opposite!" , "Have a chat, being contrary" , "Turned round" , "Talk together" .)