US prison (12)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">us prison</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 penitentiary that I've seen before include "US prison" , "Senior Catholic" , "American prison" , "stir" .)
(Other definitions for sing sing that I've seen before include "New York state prison" , "NY prison" .)