Model of the solar system (6)
I believe the answer is:
orrery
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">model of the solar system</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for orrery that I've seen before include "Clockwork model of the solar system" , "Mechanical model of the solar system" , "Err, Roy, on the side of a model of the solar system" , "Planetarium that illustrates the positions and motions of bodies in the solar system" , "Clockwork model of the sun and planets" .)