Ring-shaped; forming a ring (7)
I believe the answer is:
annular
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">ring-shaped</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >'<span class="explanation-format__original">forming a ring</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for annular that I've seen before include "in a band" , "Shaped like a ring" , "Circular" , "Ring-shaped" , "Doughnut-shaped -- a LAN run (anag)" .)