Note rebel's affectation? (6)
I believe the answer is:
facade
'affectation?' is the definition.
(thesaurus)
'note rebel's' is the wordplay.
'note' becomes 'fa' (fourth note in sol-fa notation: doh, ray, me...).
'rebel' becomes 'cade' (15th-century rebel Jack Cade).
'fa'+'cade'='FACADE'
(Other definitions for facade that I've seen before include "Deceptive outward appearance" , "Front of building or outer appearance" , "Surface of building (6)" , "Building's front" , "Series of notes" .)