US law enforcement officer (7)
I believe the answer is:
sheriff
'us law enforcement officer' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for sheriff that I've seen before include "Scottish judge" , "Crown's county officer" , "Crown executive officer in a county (England and Wales) - judge (Scotland) - lawman (US)" , "US law enforcement officer" , "Local officer" .)