Unaccompanied choral composition (5)
I believe the answer is:
motet
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">unaccompanied choral composition</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 motet that I've seen before include "Certain one is morally superior" , "Piece of sacred music" , "Short sacred vocal work" , "Totem (anag) ? anthem" , "Unaccompanied choral composition with sacred lyrics" .)