Talk in opposition (8)
I believe the answer is:
converse
'talk' is the definition.
(I know that converse is a more specific form of talk)
'in opposition' is the wordplay.
I cannot quite see how this works, but
'in opposition' could be 'con' (synonyms) and 'con' is present in the answer.
The remaining letters 'verse' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for converse that I've seen before include "express thoughts and ideas?" , "take part in discussion" , "Quite the opposite!" , "Remain silent? No" , "speak" .)