Chief Bolshevik (5)
I believe the answer is:
lenin
'chief bolshevik' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for lenin that I've seen before include "Leader of the Russian Revolution" , "Revolutionary man" , "V. I. -, Soviet politician and revolutionary" , "Communist leader" , "Vladimir Ilich Ulyanov" .)