Nervous twitch (3)
I believe the answer is:
tic
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">nervous twitch</span>' is the definition.<br/ ><span class="explanation-format__explanation">(involuntary twitch in the body)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for tic that I've seen before include "Twitch in anticipation" , "Fuel oil" , "Involuntary muscle movement" , "Spasmodic muscular twitch" , "Facial movement" .)