Legendary co-founder of Rome (5)
I believe the answer is:
remus
'legendary co-founder of rome' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for remus that I've seen before include "City founder - "uncle" storyteller" , "partner in City foundation" , "J. C. Harris's storyteller Uncle" , "murdered brother?" , "Legendary founder of Rome" .)