Unpowered aircraft (6)
I believe the answer is:
glider
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">unpowered aircraft</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 glider that I've seen before include "A sort of possum" , "Powerless aircraft" , "Plane supported by air" , "Powerless traveller" , "craft without power" .)