Follow eastern magistrate (4)
I believe the answer is:
doge
'magistrate' is the definition.
(doge is a kind of magistrate)
'follow eastern' is the wordplay.
'follow' becomes 'dog' (dog can mean to follow or torment).
'eastern' becomes 'e'.
'dog'+'e'='DOGE'
(Other definitions for doge that I've seen before include "foreign magistrate" , "Chief of ancient Venice" , "Old ruler of Venice" , "Ancient lord of Venice" , "Old Italian chief magistrate" .)