Cosmetic hard to include by noon - use sandpaper (7)
I believe the answer is:
roughen
'cosmetic hard to include by noon use sandpaper' is the definition.
I can't judge whether this definition defines the answer.
'hard to include by noon use sandpaper' is the wordplay.
'hard' becomes 'h' (abbreviation used in pencil classifications).
'to include' indicates putting letters inside.
'by' means one lot of letters go next to another.
'noon' becomes 'n' (abbreviation).
'use sandpaper' becomes 'rouge' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'n' put after 'rouge' is 'rougen'.
'h' inserted inside 'rougen' is 'ROUGHEN'.
Can you help me to learn more?
(Other definitions for roughen that I've seen before include "Make less smooth" , "Render coarse" , "Make (surface) uneven" , "rasp" , "Abrade" .)