A "terrible" Russian (4)
I believe the answer is:
ivan
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">a terrible russian</span>' is the definition.<br/ ><span class="explanation-format__explanation">(Ivan the Terrible)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(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" .)