Lithe, flexible (6)
I believe the answer is:
lissom
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">lithe</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I know that lithe can be written as lissom)</span><br/ ><br/ >'<span class="explanation-format__original">flexible</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for lissom that I've seen before include "Limber" , "Agile and lithe" , "Lithe and flexible" , "Supple, nimble" , "Supple or agile" .)