Radio set used to find celestial body (8)
I believe the answer is:
asteroid
'celestial body' is the definition.
(asteroid is a kind of celestial body)
'radio set used' is the wordplay.
'used' indicates anagramming the letters.
'radio'+'set'='radioset'
'radioset' anagrammed gives 'ASTEROID'.
'to find' is the link.
(Other definitions for asteroid that I've seen before include "looking like a star?" , "Small planet orbiting the Sun" , "Small celestial body moving around the sun" , "circling rock" , "Small body orbiting sun" .)