Old ruler who lived in Saint Petersburg (4)

I believe the answer is:

tsar

(Other definitions for tsar that I've seen before include "Formal rulings on Islamic law; was aft (anag.)" , "Once-powerful Russian" , "Russian ruler (S, not Z)" , "Nicholas II was the last" , "Title given to the kings of Bulgaria" .)

I've seen this clue in the Universal.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.