Fighting talk (6,2,4)
I believe the answer is:
battle of wits
'talk' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Perhaps there's a link between them I don't understand?
'fighting' is the wordplay.
I cannot quite understand how this works, but
'fighting' could be 'battle' and 'battle' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for battle of wits that I've seen before include "Mental duel" , "Intelligent rivalry" .)