Rascal mixing rouge (5)
I believe the answer is:
rogue
'rascal' is the definition.
(both can mean a scoundrel)
'mixing rouge' is the wordplay.
'mixing' indicates an anagram.
'rouge' with letters rearranged gives 'ROGUE'.
(Other definitions for rogue that I've seen before include "Villain - freak" , "Baddie" , "Dishonest chap; solitary (elephant)" , "Bad person" , "Old Greek" .)