Airborne youth leader in cast (6)
I believe the answer is:
flying
'airborne' is the definition.
(I've seen this before)
'youth leader in cast' is the wordplay.
'youth leader' becomes 'y' (I've seen this in other clues).
'in' means one lot of letters goes inside another.
'cast' becomes 'fling' (both can mean to throw).
'y' placed inside 'fling' is 'FLYING'.
(Other definitions for flying that I've seen before include "running fast" , "(Of flag) displayed on a flagpole" , "Getting high" , "The 22 23 show" , "Hasty" .)