Bottle stopper (4)
I believe the answer is:
cork
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">bottle stopper</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for cork that I've seen before include "Float" , "Buoyant substance from a tree" , "Irish port - something in a wine bottle?" , "Wine stopper" , "Stopper - Irish port" .)