Infamous Roman ruler (4)
I believe the answer is:
nero
'infamous roman ruler' 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 "Emperor (who fiddled while Rome burned?) d. AD68" , "Roman arsonist and fiddler" , "Imperial Roman fiddler" , "Emperor said to have fiddled as Rome burned" , "Matricidal emperor" .)