Chit-chat conceals irritation (4)
I believe the answer is:
itch
'irritation' is the definition.
(I've seen this before)
'chit-chat conceals' is the wordplay.
'conceals' indicates the answer is hidden within the clue.
'ITCH' can be found hidden inside 'chit chat'.
(Other definitions for itch that I've seen before include "Restless longing" , "Yen" , "Irritating feeling on the skin" , "Tingle" , "Contagious skin infection" .)