Held back one note to add into bundle (6)
I believe the answer is:
waited
'held back' is the definition.
('wait' can be a synonym of 'hold back')
'add into bundle' is the wordplay.
'add' becomes 'ite' (I can't justify this - if you can you should give a lot more credence to this answer).
'into' means one lot of letters goes inside another.
'bundle' becomes 'wad' (synonyms).
'ite' inserted within 'wad' is 'WAITED'.
'one note to' is the link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for waited that I've seen before include "Stayed in one place, anticipating something" , "Remained in readiness" , "Held back" , "Lingered; attended" , "Served at table or postponed some action" .)