Bolshevik's foe (4)
I believe the answer is:
tsar
'bolshevik's foe' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for tsar that I've seen before include "Powerful man" , "specific authority" , "Nicholas II was the last" , "Autocrat" , "Rats to the Russian emperor" .)