Dietary fiber (8)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
roughage
'dietary fiber' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for roughage that I've seen before include "Essential food" , "It aids digestion" , "something that can make your passing more bearable" , "Bulk" , "Indigestible fibre" .)