The most common and most likely answer to this crossword clue is the 7 letter word REDWING
I've seen this crossword clue in The Daily Telegraph
R
E
D
W
I
N
G
More clues leading to the result REDWING
Buddy explains!

The straight part
We know that "a flyer?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a flyer? = redwing.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 REDWING mean?
REDWING noun- A small thrush, Turdus iliacus, native to Eurasia, with a white eye stripe and red under-wing feathers.