Superior, say, tucking into pork pie (5)
I believe the answer is:
liege
'superior' is the definition.
(feudal term for one's superior)
'say tucking into pork pie' is the wordplay.
'say' becomes 'eg' (short for 'exempli gratia', 'for example' in Latin).
'tucking into' is an insertion indicator.
'pork pie' becomes 'lie' ('pork pie' is Cockney rhyming slang for a lie).
'eg' put within 'lie' is 'LIEGE'.
(Other definitions for liege that I've seen before include "Owing feudal allegiance" , "Belgian city or feudal chief" , "European city" , "On about one East Belgium city" , "Large Belgian city" .)