Elliptical courses of celestial objects (6)
I believe the answer is:
orbits
'elliptical courses of celestial objects' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for orbits that I've seen before include "Elliptical courses of celestial objects" , "Circles around like planet around sun" , "Circulates" , "Curved paths of planets" , "Bistro (anag)" .)