Note councillor to back revolutionary model? (8)
I believe the answer is:
crotchet
'note' is the definition.
(musical note)
'councillor to back revolutionary model?' is the wordplay.
'councillor' becomes 'cr' (I've seen this in other clues).
'back' shows that the letters should be reversed in order.
'revolutionary' becomes 'che' (Che Guevara the Marxist revolutionary).
'model?' becomes 't' (Ford Model T car).
'to' backwards is 'ot'.
'cr'+'ot'+'che'+'t'='CROTCHET'
(Other definitions for crotchet that I've seen before include "perverse notion" , "In music, it has quarter the time value of a whole note" , "Peacock's castle" , "Two quavers as one note" , "One in bar" .)