Flammable liquid (5)
I believe the answer is:
ether
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">flammable liquid</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 ether that I've seen before include "Type of chemical" , "Imaginary interstellar medium" , "Colourless volatile highly inflammable liquid" , "Anaesthetic is, strangely, there" , "It could knock you out" .)