Doughnut shape (5)
I believe the answer is:
torus
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">doughnut shape</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 torus that I've seen before include "Ring shaped like doughnut with hole" , "Doughnut-shaped solid" , "Shape of doughnut" , "Ring-shaped object" , "Ring-doughnut shape" .)