Means to cut deal: joins in talks (4)
I believe the answer is:
adze
'means to cut deal' is the definition.
(an adze is used to chop wood - deal can mean wood)
'joins in talks' is the wordplay.
'joins' becomes 'adds'.
'in talks' shows a homophone (sound like).
'adds' sounds like 'ADZE'.
(Other definitions for adze that I've seen before include "One used to cut" , "One cuts" , "Daze (anag.)" , "One might cut" , "tool for carpenter" .)