VIPs upset black market character (4)
I believe the answer is:
spiv
'black market character' is the definition.
(a criminal who deals in black market goods)
'vips upset' is the wordplay.
'upset' says the letters should be written in reverse.
'vips' written backwards gives 'SPIV'.
(Other definitions for spiv that I've seen before include "Wide boy" , "Flashy fellow who sells dodgy goods" , "Flashily dressed dodgy dealer" , "Person living off various dubious schemes" , "Arthur Daley type" .)