Go off to erase notes? (9)
I believe the answer is:
decompose
'go off' is the definition.
(I've seen this before)
'erase notes?' is the wordplay.
I cannot quite see how this works, but
'notes?' could be 'ec' and 'ec' is found within the answer.
This may be the basis of clue (or it may be nonsense).
'to' acts as a link.
Can you help me to learn more?
(Other definitions for decompose that I've seen before include "Decay, disintegrate" , "Crumble" , "as rotters do!" , "Break down" , "Scooped me in order to decay" .)