Jinx violent criminal over nothing (6)
I believe the answer is:
hoodoo
'jinx' is the definition.
(I've seen this before)
'violent criminal over nothing' is the wordplay.
'violent criminal' becomes 'hood' (I've seen this before).
'over' becomes 'o' (cricket abbreviation).
'nothing' becomes 'o' (looks like zero - 0).
'hood'+'o'+'o'='HOODOO'
(Other definitions for hoodoo that I've seen before include "Bringer of bad luck" , "bringer of misfortune" , "Thing or person thought to bring bad luck" , "Bad luck some people bring" , "Thing or person thought to cause bad luck" .)