In Whistler’s paintings note revolutionary shift (8)
I believe the answer is:
transfer
'shift' is the definition.
(synonyms)
'in whistler's paintings note revolutionary' is the wordplay.
'in' is an insertion indicator.
'whistler's' becomes 'ref's' (a referee blows a whistle).
'paintings' becomes 'art' (painting is a type of artwork).
'note' becomes 'n' (abbreviation).
'revolutionary' says the letters should be written in reverse.
'refs'+'art'='refsart'
'refsart' enclosing 'n' is 'refsnart'.
'refsnart' backwards is 'TRANSFER'.
(Other definitions for transfer that I've seen before include "Change (from one thing to another)" , "Bring over" , "Make over (property to another)" , "player's move" , "Move something from one place to another" .)