Mounting a revolt (6)
I believe the answer is:
rising
This clue is a double definition.
'mounting' is the first definition.
('rise' can be a synonym of 'mount')
'a revolt' is the second definition.
(I know that revolt can be written as rising)
(Other definitions for rising that I've seen before include "In the ascendant" , "Upward rebellion?" , "Armed revolt against authority" , "Upwardly mobile" , "Moving upwards" .)