Art is performed for part of flight (5)
I believe the answer is:
Here is my best explanation:
'part of flight' is the definition.
'art is performed' is the subsidiary indication.
'performed' indicates anagramming the letters.
'artis' with letters rearranged gives 'stair'.
'for' is the link.
(Other definitions for stair that I've seen before include "Rising step", "Part of a flight", "Word linking way and well", "One of a 15", "Way between floors", "A step on the way up or down", "Tread and riser", "Step in a series", "Indoor step" and "Step in house".)