Excellent policeman (5)
I believe the answer is:
super
I believe this clue is a double definition.
'excellent' is the first definition.
(I've seen this in another clue)
'policeman' is the second definition.
(short for superintendant)
(Other definitions for super that I've seen before include "Topnotch, terrific" , "Extremely good" , "Jolly good" , "Prefix meaning over-excellent!" , "Spiffing!" .)