Desire to take part in chit-chat (4)
I believe the answer is:
itch
'desire' is the definition.
(I know that itch is a type of desire)
'part in chit-chat' is the wordplay.
'part in' says the answer is hidden in the clue.
'ITCH' is hidden within 'chit chat'.
'to take' acts as a link.
(Other definitions for itch that I've seen before include "Impatient desire (colloq.)" , "Tickling sensation of skin" , "It must be scratched" , "Feel tingling sensation in skin" , "Tingle" .)