Bill the magistrate (4)
I believe the answer is:
beak
I believe this is a double definition.
'bill' is the first definition.
(I know that bill can be written as beak)
'magistrate' is the second definition.
(informal term)
'the' is the link.
(Other definitions for beak that I've seen before include "Bird bill; magistrate" , "Bird's bill" , "Judge - bill" , "Schoolmarm" , "Bill; nose" .)