Traitor – informant (3)
I believe the answer is:
rat
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">traitor</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(rat can mean a treacherous person)</span><br/ ><br/ >'<span class="explanation-format__original">informant</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(rat is a kind of informant)</span><br/ ><br/ ></span>
(Other definitions for rat that I've seen before include "Unpleasant character" , "Sewer rodent" , "Unpopular rodent" , "one escaping doomed vessel?" , "Despicable person" .)