Big sandwich (4)
I believe the answer is:
hero
'big sandwich' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for hero that I've seen before include "Exceptionally courageous person" , "Leander's suitor" , "object of adulation" , "Chief good guy in a book or film" , "Person distinguished by exceptional courage" .)