Loyal subject, say, tucking into pork pie (5)
I believe the answer is:
liege
'loyal subject' is the definition.
(I've seen this before)
'say tucking into pork pie' is the wordplay.
'say' becomes 'eg'.
'tucking into' means one lot of letters goes inside another.
'pork pie' becomes 'lie' (I've seen this in other clues).
'eg' going inside 'lie' is 'LIEGE'.
(Other definitions for liege that I've seen before include "Province of Belgium" , "Belgian city or feudal chief" , "Feudal vassal from a Belgian city" , "City in eastern Belgium" , "Feudal (lord); vassal" .)