Referring to the involuntary nervous system (9)
I believe the answer is:
autonomic
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">referring to the involuntary nervous system</span>' is the definition.<br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for autonomic that I've seen before include "Self-governing" , "Relating to unconsciously directed bodily functions" .)