Frank performed after John (6)
I believe the answer is:
candid
'frank' is the definition.
('candid' can be a synonym of 'frank')
'performed after john' is the wordplay.
'performed' becomes 'did' ('do' can be a synonym of 'perform').
'after' is a charade indicator (letters next to each other).
'john' becomes 'can' ('can' can be a synonym of 'john').
'did' put after 'can' is 'CANDID'.
(Other definitions for candid that I've seen before include "Frank, honest" , "Free and frank" , "Truthful and straightforward" , "Frank, forthright" , "Blunt; frank" .)