Five-sided (10)
I believe the answer is:
pentagonal
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">five-sided</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for pentagonal that I've seen before include "about certain figures in plane" , "covering several angles" .)