Study marvellous talk (6)
I believe the answer is:
confab
'talk' is the definition.
(I've seen this before)
'study marvellous' is the wordplay.
'study' becomes 'con' (conning is a kind of studying).
'marvellous' becomes 'fab' (slang abbreviation of fabulous).
'con'+'fab'='CONFAB'
(Other definitions for confab that I've seen before include "jaw" , "Chat (informal)" , "Chatter" , "casual conversation" , "Informal discussion (colloq.)" .)