One on the flighty side? (4)
I believe the answer is:
wing
'side?' is the definition.
(I've seen this in other clues)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for wing that I've seen before include "Take . . . . to fly away (4)" , "Side piece" , "Arm of building or bird" , "Flank; move quickly" , "bit of a mansion" .)