Leave, then go back and chat (6)
I believe the answer is:
gossip
'chat' is the definition.
(gossip is a kind of chat)
'leave then go back' is the wordplay.
'leave' becomes 'go' (to go is to depart or leave).
'then' becomes 'piss' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'go back' says the letters should be written backwards.
'piss' reversed gives 'ssip'.
'go'+'ssip'='GOSSIP'
'and' acts as a link.
Can you help me to learn more?
(Other definitions for gossip that I've seen before include "Idle, malicious, chatter" , "muck spreader" , "Idle prattle" , "Type of column" , "Loose malicious talk" .)