Supremely courageous (6)
I believe the answer is:
heroic
'supremely courageous' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for heroic that I've seen before include "Surpassing the ordinary, in courage say" , "Of deed or person, very brave" , "lion-hearted" , "Very brave and noble" , "Gallant" .)