Pen mate (3)
I believe the answer is:
cob
This clue might be a double definition.
'pen' is the first definition.
The answer and definition can be both animals as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'mate' is the second definition.
The definition and answer can be both things that one consumes for nourishment as well as being singular nouns.
Maybe they are linked in a way I don't understand?
Can you help me to learn more?
(Other definitions for cob that I've seen before include "Hazelnut" , "A loaf; a nut; a horse" , "Round loaf of bread" , "Source of bread" , "mount" .)