Break down chemically (7)
I believe the answer is:
degrade
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">break down chemically</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 degrade that I've seen before include "Disgrace, lower in status" , "Demean, cheapen" , "Decompose chemically" , "Break down; debase" , "reduce quality" .)