Of the outer skin (9)
I believe the answer is:
epidermal
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">of the outer skin</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for epidermal that I've seen before include "Like protective covering" , "Relating to skin surface" , "Of the outer skin" , "Like skin" .)