Thug gets gran fighting (8)
I believe the answer is:
gangster
'thug' is the definition.
(I've seen this in another clue)
'gets gran fighting' is the wordplay.
'fighting' indicates an anagram (I've seen this in other clues).
'gets'+'gran'='getsgran'
'getsgran' is an anagram of 'GANGSTER'.
(Other definitions for gangster that I've seen before include "Crook" , "Villain" , "Hoodlum" , "Mobster" , "Organised criminal" .)