Villain with terrible scar – Capone, perhaps (6)
I believe the answer is:
rascal
'villain' is the definition.
(I know that rascal is a type of villain)
'with terrible scar capone perhaps' is the wordplay.
'with' says to put letters next to each other.
'terrible' is an anagram indicator.
'capone perhaps' becomes 'al' (gangster Al Capone).
'scar' is an anagram of 'rasc'.
'rasc' put next to 'al' is 'RASCAL'.
(Other definitions for rascal that I've seen before include "Impudent child" , "Lascar (anag.)" , "mischief-maker" , "not one to be admired" , "Pickle" .)