Provider of notes is bank, half being advanced (4)
I believe the answer is:
lyre
'provider of notes' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'bank half being advanced' is the wordplay.
'bank' becomes 'rely' (I've seen this before).
'half' suggests halving the letters.
'being advanced' becomes 're' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'rely' cut in half is 'ly'.
'ly'+'re'='LYRE'
'is' acts as a link.
Can you help me to learn more?
(Other definitions for lyre that I've seen before include "Music-maker" , "Ancient stringed musical instrument with U-shaped frame" , "Harp used by ancient Greeks" , "Ancient Greek harp" , "Ancient harp-like instrument" .)