Lord, for example, tucking into Whopper (5)
I believe the answer is:
liege
'lord' is the definition.
(feudal term for a superior)
'example tucking into whopper' is the wordplay.
'example' becomes 'eg' (short for 'exempli gratia', 'for example' in Latin).
'tucking into' means one lot of letters goes inside another.
'whopper' becomes 'lie' (whopper can mean an outrageous lie).
'eg' placed into 'lie' is 'LIEGE'.
'for' acts as a link.
(Other definitions for liege that I've seen before include "Loyal subject" , "old lord" , "Vassal; city in Belgium" , "Feudal lord or Belgian city" , "Owing feudal allegiance" .)