Russian royalist (7)
I believe the answer is:
tsarist
'russian royalist' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for tsarist that I've seen before include "Artists (anag.); supporter of Russian emperor" , "Russian monarchist" , "Supporter of the Russian Empire" , "Russian emperor's supporter" , "Russian royalist" .)