VIPs overturned 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 overturned' is the wordplay.
'overturned' shows that the letters should be reversed in order.
'vips' in reverse letter order is 'SPIV'.
(Other definitions for spiv that I've seen before include "Timepiece" , "Old black marketeer" , "Flash fellow" , "Chap swindling" , "Someone making money by dubious means" .)