The rascal lived riotously (5)
I believe the answer is:
devil
'the rascal' is the definition.
(I've seen this in another clue)
'lived riotously' is the wordplay.
'riotously' is an anagram indicator.
'lived' is an anagram of 'DEVIL'.
(Other definitions for devil that I've seen before include "Fiend" , "Old Nick, Satan" , "Beast" , "See 11" , "Demon" .)