Air show stunt (4)
I believe the answer is:
loop
'air show stunt' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for loop that I've seen before include "flying stunt" , "the knowledgeable are in it" , "Oval shape" , "Circular shape of pool" , "Shape produced by a curve crossing itself" .)