Flourish or wave about (8)
I believe the answer is:
brandish
I believe this is a double definition.
'flourish' is the first definition.
(I know that flourish can be written as brandish)
'wave about' is the second definition.
(I've seen this in another clue)
(Other definitions for brandish that I've seen before include "Wave (weapon) aggressively" , "Wave as a threat" , "Wave, flourish" , "Wave like a weapon" , "Wave something about threateningly" .)