Unkeyed, as some compositions (6)
I believe the answer is:
atonal
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">unkeyed as some compositions</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 atonal that I've seen before include "(Of music) without key" , "Keyless" , "(Of music) not in any key or mode" , "Describes music not written in a particular key" , "Lacking traditional musical tone structure" .)