Target of a 1917 uprising (4)
I believe the answer is:
tsar
'target of a 1917 uprising' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tsar that I've seen before include "One associated with 26 [KREMLIN]" , "Alexander and Nicholas held this title in Russia" , "Title of Russian emperor" , "Supreme authority" , "Peter the Great, for example" .)