Eight-sided shape (7)
I believe the answer is:
octagon
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">eight-sided shape</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 octagon that I've seen before include "Eight-sided object" , "Geometric figure with eight sides" , "plane figure" , "An eight-sided polygon" , "Figure with 8 sides" .)