Protagonist some usher out (4)
I believe the answer is:
'protagonist' is the definition.
(I've seen this in another clue)
'some usher out' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'HERO' can be found hidden inside 'usher out'.
(Other definitions for hero that I've seen before include "Male protagonist" , "Chief good guy in a book or film" , "Main protagonist" , "Leading male role" , "Illustrious person" .)