Roughage (5)
I believe the answer is:
fibre
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">roughage</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 fibre that I've seen before include "Thread - strength of character" , "Threadlike substance" , "(Material composed of) thread(s)" , "Dietary material; thread" , "Brief (anag.)" .)