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 "one on the way up", "Flight unit", "Step as part of flight", "means to go down", "Set of steps", "this could get one down", "something of a case", "One step of a flight", "Step in a series" and "single step in a series".)