Gossip, blatantly lying, answering back initially (4)
I believe the answer is:
blab
'gossip' is the definition.
(blab can mean to gossip or reveal secrets)
'blatantly lying answering back initially' is the wordplay.
'initially' suggests taking the first letters.
The initial letters of 'blatantly lying answering back' is 'BLAB'.
(Other definitions for blab that I've seen before include "Shoot one's mouth off" , "Tells tales" , "Spill the beans" , "Divulge secret information" , "Tell tales" .)