Elfin (6)
I believe the answer is:
impish
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">elfin</span>' is the definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for impish that I've seen before include "Teasingly mischievous" , "Wicked" , "Mischievous like small fairy" , "Playful" , "Naughty" .)