Kind of reaction or instinct (3)
I believe the answer is:
gut
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">kind of reaction</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >'<span class="explanation-format__original">instinct</span>' is the second definition.<br/ ><br/ ></span>
(Other definitions for gut that I've seen before include "Intestine, or the stomach" , "corporation" , "restricted passage" , "Internal channel" , "Food processor" .)