Most airlines provide this flight (5)
I believe the answer is:
stair
'this flight' is the definition.
(I've seen this before)
'most airlines provide' is the wordplay.
'provide' indicates a hidden word.
'STAIR' is hidden in the letters of 'most airlines'.
(Other definitions for stair that I've seen before include "Flight unit" , "one on the way up" , "something of a case" , "that's between levels" , "Step as part of flight" .)