Underwent (chemical) change (7)
I believe the answer is:
reacted
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">underwent chemical change</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 reacted that I've seen before include "Responded to a stimulus" , "Showed a response" .)