The most common and most likely answer to this crossword clue is the 4 letter word BOAS
B
O
A
S
Buddy explains!
The straight part
We know that "coils of feathers, say" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case coils of feathers, say = boas.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 BOAS mean?
BOAS noun- Any of a group of large American snakes, of the genus Boa, subfamily Boinae, or family Boidae, including the boa constrictor, the emperor boa of Mexico, and the chevalier boa of Peru.
- (plural "boas") A type of scarf typically made from feathers.