Notes on paper occasionally (9)
I believe the answer is:
sometimes
'occasionally' is the definition.
(I've seen this in another clue)
'notes on paper' is the wordplay.
'notes' becomes 'some' ('so' and 'me' are musical notes).
'on' says to put letters next to each other (in a down clue, letters appear on others).
'paper' becomes 'times' (The Times newspaper).
'some'+'times'='SOMETIMES'
(Other definitions for sometimes that I've seen before include "Not always" , "Seem moist (anag.)" , "On occasion" , "Occasionally available" .)