Champion of the Romans (4)
I believe the answer is:
hero
'champion' is the definition.
(I know that champion can be written as hero)
'of the romans' is the wordplay.
'of' indicates the answer is hidden within the clue.
'HERO' is hidden in the letters of 'the romans'.
(Other definitions for hero that I've seen before include "Principal male character in a play, movie, novel or poem" , "Principal male figure in a story" , "Admired champion" , "Man of great courage and deeds" , "priestess of Aphrodite" .)