Police informer (4)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">police informer</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for stool pigeon that I've seen before include "Police informer" , "Grass" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">police informer</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for nark that I've seen before include "source of irritation" , "Cooper's .... was old police informer" , "Cause minor annoyance" , "Keep an eye" , "Habitual grumbler" .)