Converse (4)
'converse' is the definition.
(I know that chat is a type of converse)
This is all the clue.
(Other definitions for chat that I've seen before include "Bird - talk easily" , "Talk easily; songbird" , "tittle-tattle" , "Communication" , "Casual conversation" .)
(Other definitions for talk that I've seen before include "Chat" , "Conversation" , "Discussion" , "that's said to be cheap" , "Gas" .)