Make effort to remember note by rebel (8)
I believe the answer is:
memorise
'make effort to remember' is the definition.
(commit to memory)
'note by rebel' is the wordplay.
'note' becomes 'memo' (a memo is a short note).
'by' means one lot of letters go next to another.
'rebel' becomes 'rise' (synonyms).
'memo'+'rise'='MEMORISE'
(Other definitions for memorise that I've seen before include "Commit information to the mind" , "Learn by heart" .)