Roman tyrant (4)
I believe the answer is:
nero
'roman tyrant' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for nero that I've seen before include "Roman emperor who fiddled while Rome burned" , "Ancient Roman emperor" , "Fiddling Roman emperor" , "Roman 9" , "Roman emperor on the fiddle?" .)