Small celestial body (8)
I believe the answer is:
asteroid
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">small celestial body</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for asteroid that I've seen before include "way-out rock" , "Ceres, say" , "Small planet revolving round the sun" , "circling rock" , "Rocky body in orbit" .)