Flying machines (8)
I believe the answer is:
aircraft
'flying machines' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for aircraft that I've seen before include "Machine capable of flight" , "Airbus A330 or 380, say" , "Airbus A380 or Boeing 777, say" , "means of transport" , "Airbus A380 or Boeing 747 say" .)