Abdicator of 1917 (4)
I believe the answer is:
tsar
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">abdicator of 1917</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for tsar that I've seen before include "Powerful man" , "Title of Russian emperor" , "Supreme authority" , "Star for a Russian emperor" , "Male monarch" .)