Swear in the middle of discussion (4)
I believe the answer is:
cuss
'swear' is the definition.
(synonyms)
'middle of discussion' is the wordplay.
'middle of' indicates the answer is hidden within the clue (the answer is somewhere in the middle of the clue).
'CUSS' is hidden within 'discussion'.
'in the' is the link.
(Other definitions for cuss that I've seen before include "Oath; (annoying sort of) person" , "Swear (slang)" , "Use bad language (informal)" , "Blaspheme" , "Stubborn person" .)