Desire revealed in chit-chat (4)
I believe the answer is:
itch
'desire' is the definition.
(itch is a kind of desire)
'revealed in chit-chat' is the wordplay.
'revealed in' says the answer is hidden in the clue.
'ITCH' is hidden within 'chit chat'.
(Other definitions for itch that I've seen before include "Longing; anag. of 19" , "Hankering" , "great desire" , "Constant desire" , "A nagging desire" .)