Second-rate and badly dressed but put on a big act (7)
I believe the answer is:
bragged
'put on a big act' is the definition.
'second-rate and badly dressed' is the wordplay.
'second rate' becomes 'b'.
'and' is a charade indicator (letters next to each other).
'badly dressed' becomes 'ragged'.
'b'+'ragged'='BRAGGED'
'but' acts as a link.
(Other definitions for bragged that I've seen before include "Crew" , "Boasted" , "Blew one's own trumpet" .)