Note from the east to bring about an agreement without delay (9)
I believe the answer is:
immediate
'without delay' is the definition.
(I've seen this in another clue)
'note from the east to bring about' is the wordplay.
'note' becomes 'mi' (musical note).
'from the east' says the letters should be written in reverse (on a map from right to left).
'to bring about' becomes 'mediate' (I can't explain this - if you can you should give a lot more credence to this answer).
'mi' backwards is 'im'.
'im'+'mediate'='IMMEDIATE'
'an agreement' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for immediate that I've seen before include "Instant" , "Instantaneous" , "Prompt,straightaway" , "Occurring without delay" , "Involving no delay" .)