Preparation for course: note start of lessons separately introduced in Term One after review (9)

I believe the answer is:
enrolment
'preparation' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'course note start of lessons separately introduced in term one after review' is the wordplay.
I cannot really understand how this works, but
'course' could be 'n' and 'n' is located in the answer.
'note' could be 'me' (alternative spelling the musical note mi) and 'me' is located in the answer.
'of' could be 'o' and 'o' is present in the answer.
This explanation may well be incorrect...
'for' is the link.
Can you help me to learn more?
(Other definitions for enrolment that I've seen before include "Registration" , "matriculation" , "signing up" , "Joining" , "Act of entering on a list of members" .)