Group of notes in harmony (5)
I believe the answer is:
chord
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">group of notes in harmony</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for chord that I've seen before include "line for mathematicians" , "Notes struck together" , "Combination of notes sounded in harmony" , "Group of notes sounded together" , "Number of notes played together" .)