Tattletale
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">tattletale</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for rat that I've seen before include "Betrayer" , "Tell-tale" , "Destructive rodent" , "Domestic rodent" , "one escaping doomed vessel?" .)