Retired old man’s boring meal (6)
I believe the answer is:
repast
'meal' is the definition.
(repast can mean a meal)
'retired old man's boring' is the wordplay.
'retired' becomes 'ret' (e.g. following the name of a retired army officer).
'old man's' becomes 'pas' (both can mean someone's father).
'boring' indicates putting letters inside (to bore something can mean to drill into it).
'ret' going around 'pas' is 'REPAST'.
(Other definitions for repast that I've seen before include "A meal concerning time gone by" , "Feast, meal" , "Prates about meal" , "Banquet" , "Food - tapers (anag)" .)