Russian ruler back in Ezra’s time (4)
I believe the answer is:
tsar
'russian ruler' is the definition.
(I've seen this before)
'back in ezra's time' is the wordplay.
'back' says the letters should be written backwards.
'in' says the answer is hidden in the clue.
'rast' is hidden within 'ezras time'.
'rast' reversed gives 'TSAR'.
(Other definitions for tsar that I've seen before include "Tyrant" , "Peter the Great, for example" , "Russian monarch" , "Potentate" , "Powerful man" .)