Vandalise six notes (6)
I believe the answer is:
deface
'vandalise' is the definition.
(I've seen this before)
'six notes' is the wordplay.
I cannot really understand how this works, but
'notes' could be 'fa' and 'fa' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for deface that I've seen before include "six notes?" , "Spoil surface of, mar" , "ruin" , "Spoil or damage the surface of" , "Wantonly spoil the look of" .)