Riposte; laboratory vessel (6)
I believe the answer is:
retort
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">riposte</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I know that riposte can be written as retort)</span><br/ ><br/ >'<span class="explanation-format__original">laboratory vessel</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ ></span>
(Other definitions for retort that I've seen before include "Chem. flask; sharp answer" , "A sharp reply or vessel used in distilling" , "Sharp response; lab item" , "Riposte, reply" , "Still" .)