A "terrible" Russian (4)
I believe the answer is:
ivan
'a terrible russian' is the definition.
(Ivan the Terrible)
This is the entire clue.
(Other definitions for ivan that I've seen before include "One Day in the Life of - Denisovich (Solzhenitsyn)" , "in Russian history" , "Chap" , "Vain (anag) - Tsar of Russia" , "First tsar of Russia" .)