Strong alkaline solution (3)
I believe the answer is:
lye
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">strong alkaline solution</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for lye that I've seen before include "Alkaline solution used for washing" , "Cleansing alkaline fluid" , "Alkali washing solution" , "Strong alkaline solution" , "Alkaline liquid" .)