Archie's boss, in detective fiction (4)
I believe the answer is:
'archie's boss in detective fiction' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for nero that I've seen before include "Notorious Roman emperor, d. AD 68" , "Fiddling Roman emperor" , "Cruel Roman emperor" , "Imperial Roman fiddler" , "Roman tyrant" .)