Cop's contact (7)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">cop's contact</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 stoolie that I've seen before include "Grass" , "Informer or decoy for the cops" , "Police informer" , "Singer" .)