Puts a ring round former potentate (4)

I believe the answer is:

tsar

I'm a little stuck... Click here to teach me more about this clue!

'potentate' is the definition.
(I've seen this before)

'puts a ring round former' is the wordplay.
'TSAR' is hidden within the letters.
But, I am uncertain how the hidden word is indicated.

Can you help me to learn more?

(Other definitions for tsar that I've seen before include "Person in charge" , "Star for a Russian emperor" , "Rats (anag)" , "Nicholas II was the last" , "Male monarch" .)

I've seen this clue in the Sydney Morning Herald.

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.