Wide boy seeking profit in villainy, primarily (4)
I believe the answer is:
spiv
'wide boy' is the definition.
(I've seen this before)
'seeking profit in villainy primarily' is the wordplay.
'primarily' suggests taking the first letters.
The initial letters of 'seeking profit in villainy' is 'SPIV'.
(Other definitions for spiv that I've seen before include "Flashy black-marketeer" , "Arthur Daley type" , "Flashily dressed dodgy dealer" , "WW two black-marketeer" , "Unscrupulous dealer" .)