Thrash repulsive criminal (9)
I believe the answer is:
pulverise
'thrash' is the definition.
('thrash'->'pulverize' is in my internal thesaurus and 'ize'->'ise')
'repulsive criminal' is the wordplay.
'criminal' is an anagram indicator.
'repulsive' anagrammed gives 'PULVERISE'.
(Other definitions for pulverise that I've seen before include "Crush thoroughly in a repulsive way" , "Crush thoroughly in repulsive manner" , "Beat to a pulp" , "Reduce to dust (S, not Z)" , "Grind to powder" .)