More than one lawman spoils artist (8)
I believe the answer is:
marshals
'more than one lawman' is the definition.
(marshal is a kind of lawman)
'spoils artist' is the wordplay.
'spoils' becomes 'mars' ('mar' can be a synonym of 'spoil').
'artist' becomes 'hals' (I've seen this before).
'mars'+'hals'='MARSHALS'
(Other definitions for marshals that I've seen before include "Arranges" , "Chief officers" , "Officials" , "Crowd-controllers at large public events" .)