First premier of the Soviet Union (5)
I believe the answer is:
lenin
'first premier of the soviet union' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for lenin that I've seen before include "Soviet Union's first premier" , "Leader of the Russian Revolution" , "Early Soviet leader" , "Linen for Communist" , "Marxist theoretician" .)