Painter appears to swindle firm (9)
I believe the answer is:
constable
'painter' is the definition.
(I know that Constable is a painter)
'to swindle firm' is the wordplay.
'to swindle' becomes 'con' ('con' can be a synonym of 'swindle').
'firm' becomes 'stable' (similar in meaning).
'con'+'stable'='CONSTABLE'
'appears' acts as a link.
(Other definitions for constable that I've seen before include "Bobby" , "Did he have a brush" , "He painted" , "the governor of a royal castle" , "Force member" .)