Good marks for preparing cheese (7)
I believe the answer is:
grating
'preparing cheese' is the definition.
(as in grating cheese)
'good marks' is the wordplay.
'good' becomes 'g' (abbreviation).
'marks' becomes 'rating' (both can mean an assessment of something).
'g'+'rating'='GRATING'
'for' acts as a link.
(Other definitions for grating that I've seen before include "Jarring" , "Rasping - grille" , "Harsh - framework of crossed bars" , "Frame of bars supporting a fire" , "Frame of iron bars to block passage but allow air" .)