Rocks in a cocktail (3)
I believe the answer is:
ice
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">rocks in a cocktail</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 ice that I've seen before include "Glaze" , "Formality" , "Solid water" , "Finish decorating the Christmas cake" , "Cooler" .)