Mattress filling (5)
I believe the answer is:
kapok
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">mattress filling</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 kapok that I've seen before include "Stuffing material" , "A plant fibre used for stuffing and insulation" , "Silk-cotton" , "filler" , "Natural stuffing fibre" .)