Bartender's "rocks” (3)
I believe the answer is:
ice
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">bartender's rocks</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 "Solid H2O" , "Formality" , "kill American" , "It's cold and slippy" , "If it's thin, skating on it can be dangerous" .)