Part of a flight coming from best airport (5)
I believe the answer is:
stair
'part of a flight' is the definition.
(I've seen this before)
'from best airport' is the wordplay.
'from' says the answer is hidden in the clue.
'STAIR' is hidden within 'best airport'.
'coming' is the link.
(Other definitions for stair that I've seen before include "Bit of a flight!" , "Indoor step" , "Word linking way and well" , "Tarsi (anag)" , "something of a case" .)