Mistaken to block return of unusual bravery (7-2)
I believe the answer is:
derring-do
'bravery' is the definition.
(I've seen this before)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for derring-do that I've seen before include "Brave and heroic feat(s)" , "Literary expression for heroic courage or action" , "Brave acts" , "Courageous action" , "Daring deeds" .)