Corrosive liquid (4)
I believe the answer is:
acid
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">corrosive 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 acid that I've seen before include "Caustic and biting" , "Sour, sharp-tasting" , "Sarcastic - tart" , "Battery fluid" , "Hallucinogenic drug" .)