1) Beat cop 2) Flatfoot 3) Law officer 4) Lawman 5) Officer on the beat 6) One keeping a beat 7) One who keeps a beat 8) Peace officer Found on https://www.crosswordclues.com/clue/patrolman
Pa·trol'man noun ; plural Patrolmen One who patrols; a watchman; especially, a policeman who patrols a particular precinct of a town or city. Found on http://www.encyclo.co.uk/webster/P/34