It’s shortened notes (3)
I believe the answer is:
tis
I believe this is a double definition.
'it's shortened' is the first definition.
('tis' is short for 'it is' or 'it's')
'notes' is the second definition.
(more than one ti, a musical note)
(Other definitions for tis that I've seen before include "I confirm the identity of" , "Pacific trees" , "It is shortened" , "... the season to be jolly" , "McCourt work" .)