Valiantly (6)
I believe the answer is:
boldly
'valiantly' is the definition.
(thesaurus)
This is all the clue.
(Other definitions for boldly that I've seen before include "Confidently, daringly" , "With courage" , "''To ... go where no man has gone before'' (Star Trek mission)" , "Confidently and courageously" , "Audaciously" .)