In macaroni, once, a pungent ingredient (5)
I believe the answer is:
onion
'pungent ingredient' is the definition.
The answer and definition 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?
'in macaroni once a' is the wordplay.
'in' indicates the answer is hidden within the clue.
'ONION' is hidden within 'macaroni once a'.
Can you help me to learn more?
(Other definitions for onion that I've seen before include "One may be set" , "Tear-jerking bulb" , "Bulb used as a vegetable" , "associated with 26 [TRIPE] ?" , "Alliaceous plant" .)