Revolutionary nut reigns, revolting (9)
I believe the answer is:
insurgent
'revolting' is the definition.
(I've seen this before)
'revolutionary nut reigns' is the wordplay.
'revolutionary' indicates anagramming the letters.
'nut'+'reigns'='nutreigns'
'nutreigns' with letters rearranged gives 'INSURGENT'.
(Other definitions for insurgent that I've seen before include "freedom fighter" , "Revolting" , "Rebel, revolutionary" , "Unresting like a rebel" , "rising" .)