"Cops” sound (5)
I believe the answer is:
siren
'cops sound' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for siren that I've seen before include "Nymph supposed to have lured sailors to destruction on rocks" , "Temptress - warning device" , "Warning signal generator" , "Loud whistle or dangerous woman" , "Warning sound" .)