Cosa Nostra (5)
I believe the answer is:
mafia
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">cosa nostra</span>' is the definition.<br/ ><span class="explanation-format__explanation">(Cosa Nostra is an Italian term for the mafia)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for mafia that I've seen before include "organised criminals" , "International crime organisation originating in Sicily" , "Criminal organisation also known as Cosa Nostra" , "Gangsters" , "Sicilian secret society" .)