Cay; eyot (5)
I believe the answer is:
islet
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">cay</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >'<span class="explanation-format__original">eyot</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for islet that I've seen before include "Tiles (anag.)" , "Tiles to make a small island" , "Ait or key" , "Ait or eyot" , "Detached bit of land" .)