Stealthy assassin (5)
I believe the answer is:
ninja
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">stealthy assassin</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 ninja that I've seen before include "Ninjutsu expert" , "Teenage Mutant ... Turtle (toy)" , "Stealthy Japanese fighter" , "Stealthy Japanese spy" , "Teenage Mutant -- Turtles (TV/film)" .)