Flying force was airborne briefly — a lottery (6)
I believe the answer is:
raffle
'a lottery' is the definition.
(I know that raffle is a type of lottery)
'flying force was airborne briefly' is the wordplay.
'flying force' becomes 'RAF' (Royal Air Force).
'was airborne' becomes 'flew' (flew in the air).
'briefly' means to remove the last letter.
'flew' with its last letter taken away is 'fle'.
'raf'+'fle'='RAFFLE'
(Other definitions for raffle that I've seen before include "charity event" , "Fund-raising draw" , "Lottery with goods as prizes" , "Lotto" , "offer as prize" .)