The most common and most likely answer to this crossword clue is the 9 plus 6 letter word FEATHERED FRIEND
I've seen this crossword clue in The Daily Telegraph
F
E
A
T
H
E
R
E
D
F
R
I
E
N
D
Buddy explains!
The straight part
We know that "‘ally with wings’" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case ‘ally with wings’ = feathered friend.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.