Chuck senior's fruit? (10)
I believe the answer is:
elderberry
'chuck' is the definition.
The definition and answer can be both things that one consumes for nourishment as well as being singular nouns.
Maybe there's an association between them I don't understand?
'senior's fruit?' is the wordplay.
'senior' becomes 'elder' ('elder' can be similar in meaning to 'senior').
'fruit?' becomes 'berry' (berry is a kind of fruit).
'elder'+'berry'='ELDERBERRY'
(Other definitions for elderberry that I've seen before include "Tree fruit used for wine" , "A blue-black fruit" , "Wine or jelly can be made from this" , "Fruit used to make wine" , "Fruit used for cordial" .)