Ten-sided shape (7)
I believe the answer is:
decagon
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">ten-sided shape</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 decagon that I've seen before include "Go, dance on geometric figure with ten sides" , "A polygon -- eg can-do (anag)" , "Figure with 10 sides" , "Ten-sided plane figure" , "Plane shape" .)