The most common and most likely answer to this crossword clue is the 9 letter word LYREBIRDS
L
Y
R
E
B
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Buddy explains!
The straight part
We know that "fliers" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case fliers = lyrebirds.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 LYREBIRDS mean?
LYREBIRDS noun- Either of two large ground-dwelling Australian songbirds, of the genus Menura, named because of the beautiful tail feathers of the male of one species, the superb lyrebird (Menura novaehollandiae), which can be erected to look like a lyre, and notable for their extraordinary ability to mimic natural and artificial sounds from their environment.