Lawman about to get work (3)
I believe the answer is:
cop
'lawman' is the definition.
(cop is a kind of lawman)
'about to get work' is the wordplay.
'about' becomes 'c' (abbreviation for 'circa').
'to get' is a charade indicator (letters next to each other).
'work' becomes 'op' (abbreviation for opus).
'c'+'op'='COP'
(Other definitions for cop that I've seen before include "Policeman (informal)" , "Policeman (slang)" , "Police officer (slang)" , "Policeman (sl)" , "Member of the police force and an arrest" .)