Flamboyant self-assurance (7)
I believe the answer is:
panache
'flamboyant self-assurance' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for panache that I've seen before include "A dashing manner" , "'Dash, flair (7)'" , "Brio - flair" , "Great style" , "Grand manner, theatricality" .)