The most common and most likely answer to this crossword clue is the 7 letter word MARABOU
I've seen this crossword clue in The Guardian
M
A
R
A
B
O
U
Buddy explains!
The straight part
We know that "bird" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case bird = marabou.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 MARABOU mean?
MARABOU noun- Leptoptilos crumeniferus, a large wading bird native to Africa, with a naked head and neck adapted for scavenging.
- A person, five-eighths of whose ancestry is black; the offspring of a mulatto and a griffe.
- A kind of thrown raw silk, naturally nearly white, but capable of being dyed without scouring.
- A thin fabric made from this silk, as for scarfs.