Deceive with terrific talk (6)
I believe the answer is:
confab
'talk' is the definition.
(I've seen this before)
'deceive with terrific' is the wordplay.
'deceive' becomes 'con' (I've seen this before).
'with' means one lot of letters go next to another.
'terrific' becomes 'fab'.
'con'+'fab'='CONFAB'
(Other definitions for confab that I've seen before include "jaw" , "Informal discussion (colloq.)" , "gossip" , "Informal conversation" , "Chat (informal)" .)