Key rings? (6)
I believe the answer is:
atolls
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">key rings?</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 atolls that I've seen before include "Ring-shaped coral reefs enclosing lagoons" , "Coral reef islands" , "Ring-shaped coral islands" .)