Still in airliner travelling (5)
I believe the answer is:
inert
'still' is the definition.
(I've seen this in another clue)
'in airliner travelling' is the wordplay.
'in' says the answer is hidden in the clue.
'INERT' can be found hidden inside 'airliner travelling'.
(Other definitions for inert that I've seen before include "Sluggish, still" , "Chemically inactive" , "Devoid of motion or change" , "Unreactive; still" , "lazy" .)