Outer layer of a seed (5)
I believe the answer is:
testa
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">outer layer of a seed</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for testa that I've seen before include "cover for a seed" , "Hard shell" , "Protective covering" , "Botanical term" , "hard case" .)