Meal -- father tucks into what's left (6)
I believe the answer is:
repast
'meal' is the definition.
('repast' can be a synonym of 'meal')
'father tucks into what's left' is the wordplay.
'father' becomes 'pa' (pa is a kind of father).
'tucks into' indicates putting letters inside.
'what's left' becomes 'rest' (I've seen this in other clues).
'pa' placed inside 'rest' is 'REPAST'.
(Other definitions for repast that I've seen before include "Banquet" , "Food - tapers (anag)" , "Prates about meal" , "Feast, meal" , "Something to eat" .)