Gang leader left ride flying aircraft (6)
I believe the answer is:
glider
'aircraft' is the definition.
(glider is a kind of aircraft)
'gang leader left ride flying' is the wordplay.
'leader' indicates taking the first letters.
'left' becomes 'l' (common abbreviation).
'flying' indicates an anagram (letters fly around into new positions).
The initial letter of 'gang' is 'g'.
'ride' with letters rearranged gives 'ider'.
'g'+'l'+'ider'='GLIDER'
(Other definitions for glider that I've seen before include "Plane supported by air" , "Engineless plane" , "Kind of aircraft without an engine" , "Girdle for silent flier" , "Powerless aircraft" .)