Thief, burglar (6)
I believe the answer is:
robber
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">thief</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(robber is a kind of thief)</span><br/ ><br/ >'<span class="explanation-format__original">burglar</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ ></span>
(Other definitions for robber that I've seen before include "Violent thief" , "Mugger" , "Burglar" , "One who steals" , "Property stealer" .)