Nothing in urge to reform villain (5)
I believe the answer is:
rogue
'villain' is the definition.
(rogue is a kind of villain)
'nothing in urge to reform' is the wordplay.
'nothing' becomes 'O' (looks like zero - 0).
'in' is an insertion indicator.
'to reform' is an anagram indicator (letters in a new form).
'urge' with letters rearranged gives 'rgue'.
'o' placed into 'rgue' is 'ROGUE'.
(Other definitions for rogue that I've seen before include "Rascal or reprobate" , "Prankster" , "Unprincipled man" , "Fraud" , "Profligate" .)