Original idea losing million before bringing in top aircraft (6)
I believe the answer is:
glider
'aircraft' is the definition.
(glider is a kind of aircraft)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for glider that I've seen before include "Engineless plane" , "Sailplane" , "Flying machine without engine" , "Unpowered plane" , "Plane supported by air" .)