Champagne stopper (4)
I believe the answer is:
cork
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">champagne stopper</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 cork that I've seen before include "Stopper - Irish port" , "Wine bottle plug" , "Irish port - something in a wine bottle?" , "Common bottle stopper" , "Buoyant substance from a tree" .)