Anything wrong with a thug? (5)
I believe the answer is:
aught
'anything' is the definition.
(I've seen this in another clue)
'wrong with a thug?' is the wordplay.
'wrong' indicates an anagram.
'with' says to put letters next to each other.
'a' next to 'thug' is 'athug'.
'athug' anagrammed gives 'AUGHT'.
(Other definitions for aught that I've seen before include "Nothing" , "Anything at all (archaic)" , "Emphatically anything" , "Anything (Shakespearean)" .)