Setter accommodating pilots aboard special flying machine (9)
I believe the answer is:
spaceship
'flying machine' is the definition.
(vehicle for flying into space)
'setter accommodating pilots aboard special' is the wordplay.
I cannot really understand how this works, but
'setter' could be 'i' (the person that set the crossword) and 'i' is found within the answer.
'special' could be 'sp' and 'sp' is found within the answer.
This may be the basis of clue (or it may be nonsense).
(Other definitions for spaceship that I've seen before include "Craft to travel outside the Earth's atmosphere" , "Craft for an astronaut" , "long-distance traveller?" , "Interplanetary craft" , "long-distance vessel" .)