Lawman spoils Henry (7)
I believe the answer is:
marshal
'lawman' is the definition.
(I know that marshal is a type of lawman)
'spoils henry' is the wordplay.
'spoils' becomes 'mars' ('mar' can be a synonym of 'spoil').
'henry' becomes 'hal' (short for Henry).
'mars'+'hal'='MARSHAL'
(Other definitions for marshal that I've seen before include "Event supervisor" , "Maybe a bulldog" , "Assemble and arrange" , "Sports event official" , "Mobilise -- US law-enforcement officer" .)