Police van (5,5)
I believe the answer is:
black maria
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">police van</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for black maria that I've seen before include "vehicle for criminals" , "Nick vehicle" , "Van with criminals" , "Old police van for transporting prisoners" , "Police prisoners' transport" .)