Celestial hunter (5)
I believe the answer is:
'celestial hunter' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for orion that I've seen before include "Constellation that includes Betelgeuse" , "Mythical great hunter" , "Rigel constellation" , "Heavenly figure" , "His belt is in the heavens" .)