Venetian magistrate (4)
I believe the answer is:
doge
'venetian magistrate' is the definition.
(historical term for the chief magistrate of Venice)
This is the entire clue.
(Other definitions for doge that I've seen before include "Title of former ruler of Venice" , "Ancient lord of Venice" , "Old lord of Venice" , "Former title of the chief magistrate in Venice" , "Historically, the chief magistrate of Venice or Genoa" .)