Bolshevik leader (5)
I believe the answer is:
lenin
'bolshevik leader' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for lenin that I've seen before include "Vladimir Ilich Ulyanov" , "Head of the Communist state after the fall of the Tsar" , "Marxist theoretician" , "Leader of the Russian Revolution" , "Communist leader" .)