Scent sensor (4)
I believe the answer is:
nose
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">scent sensor</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 nose that I've seen before include "front part of vehicle" , "Faculty for detecting" , "Aroma of wine" , "scent" , "Front of an aircraft" .)