Stave character (4)
I believe the answer is:
clef
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">stave character</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 clef that I've seen before include "Sign of (musical) pitch" , "Symbol on a stave to show the pitch" , "Treble or bass on a stave" , "Musical notation on a staff" , "Item of musical notation" .)