Coconut husk fiber (4)
I believe the answer is:
coir
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">coconut husk fiber</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 coir that I've seen before include "Fibre from coconut husks" , "Coarse fibre from a coconut husk" , "Coconut husk fibre used for making matting" , "growing medium" .)