The most common and most likely answer to this crossword clue is the 8 letter word PORRIDGE
I've seen this crossword clue in Financial Times
P
O
R
R
I
D
G
E
Buddy explains!

The straight part
We know that "Bird/food" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case bird/food = porridge.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does PORRIDGE mean?
PORRIDGE noun- A dish made of grain or legumes, milk and/or water, heated and stirred until thick and typically eaten for breakfast.
- Oatmeal porridge.
- A prison sentence.
- A type of thick soup or stew, especially thickened with barley.