Notice it's somewhat smaller but it's very clean (8)
I believe the answer is:
spotless
'very clean' is the definition.
(I've seen this before)
'notice it's somewhat smaller but' is the wordplay.
'notice' becomes 'spot' (spot can mean to notice or observe).
'it's somewhat' means to remove the last letter (some but not all of the word).
'smaller' becomes 'less' (less great in size).
'but' becomes 's' (I can't justify this - if you can you should believe this answer much more).
'less' with its last letter taken off is 'les'.
'spot'+'les'+'s'='SPOTLESS'
'it's' is the link.
Can you help me to learn more?
(Other definitions for spotless that I've seen before include "Immaculate" , "How Lady Macbeth wanted to be" , "Free from blemish" , "showing no sign of acne?" , "Fully clean" .)