Desire firm check (5)
I believe the answer is:
covet
'desire' is the definition.
(I've seen this in another clue)
'firm check' is the wordplay.
'firm' becomes 'co' (a firm is a company).
'check' becomes 'vet' (to vet someone is to check their background).
'co'+'vet'='COVET'
(Other definitions for covet that I've seen before include "Hanker after" , "Complacent" , "Long enviously (to have something)" , "Crave, long to possess" , "Desire eagerly" .)