Small mammal; sneaky person (6)
I believe the answer is:
weasel
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">small mammal</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">sneaky person</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 weasel that I've seen before include "Sneaky person - small, long-necked carnivorous animal" , "Rat" , "Double-dealer" , "One deceiving" , "Musteline animal" .)