Cleaner matter under bottom of carpet (6)
I believe the answer is:
tissue
This clue might be a double definition.
'cleaner' is the first definition.
(paper that cleans)
'matter under bottom of carpet' is the second definition.
'tissue' can be an answer for 'matter' (I have seen 'Bodily matter' mean 'tissue' so perhaps 'matter' could also mean 'tissue'). I am not certain of the 'under bottom of carpet' bit.
Can you help me to learn more?
(Other definitions for tissue that I've seen before include "series of lies" , "Sneeze catcher?" , "load of lies?" , "Maybe lies" , "Absorbent paper, used as handkerchief, say" .)
