Lagoon site (5)
I believe the answer is:
atoll
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">lagoon site</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 atoll that I've seen before include "Bikini for one" , "tropical paradise?" , "Land around a lagoon, such as Bikini" , "Coral circle" , "land threatened by rising sea levels" .)