Circle section (3)
I believe the answer is:
arc
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">circle section</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 arc that I've seen before include "Half-moon" , "Part of a circular line" , "development of plot" , "Segment of circumference" , "Curved section" .)