Fake note – what a pity! (5)
I believe the answer is:
shame
'what a pity' is the definition.
(I've seen this before)
'fake note' is the wordplay.
'fake' becomes 'sham' ('sham' can be a synonym of 'fake').
'note' becomes 'e' (musical note**).
'sham'+'e'='SHAME'
(Other definitions for shame that I've seen before include "Disgrace, intense regret" , "show up" , "pity!" , "scandal" , "Regrettable thing" .)