Wide boy has upset bigwigs (4)
I believe the answer is:
spiv
'wide boy' is the definition.
(I've seen this before)
'upset bigwigs' is the wordplay.
'upset' shows that the letters should be reversed in order.
'bigwigs' becomes 'vips' (I've seen this in another clue).
'vips' reversed gives 'SPIV'.
'has' acts as a link.
(Other definitions for spiv that I've seen before include "Arthur Daley type" , "Flashy dresser who makes a living by dubious means" , "Flashy rogue" , "Disreputable dealer" , "Disreputable and flashy man" .)