Police shocker (5)
I believe the answer is:
taser
'police shocker' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for taser that I've seen before include "The weapon delivers a temporary paralysing electric shock" , "Paralysing device used by police" , "Stunning weapon" , "Gun firing electrified barbs" , "A temporary stunner?" .)