Planet demoted in 2006 (5)
I believe the answer is:
pluto
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">planet demoted in 2006</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 pluto that I've seen before include "Solar system body" , "recently losing status within star system" , "Greek god - cartoon dog" , "Ninth planet of solar system" , "it's another world there" .)