Detain criminal with my explosive (8)
I believe the answer is:
dynamite
'explosive' is the definition.
(dynamite is a kind of explosive)
'detain criminal with my' is the wordplay.
'criminal with' indicates an anagram.
'detain' mixed up with 'my' gives 'DYNAMITE'.
(Other definitions for dynamite that I've seen before include "Nobel's invention" , "an exciting thing" , "Exciting person - explosive" , "A1" , "Explosive - amazing thing" .)