The most common and most likely answer to this crossword clue is the 8 letter word HALTERES
H
A
L
T
E
R
E
S
Buddy explains!
The straight part
We know that "Aids to balance in flight" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case aids to balance in flight = halteres.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 HALTERES mean?
HALTERES noun- A small knobbed structure in some two-winged insects, one of a pair that are flapped rapidly and function as accelerometers to maintain stability in flight.