Brief note on account book showing addition to staff (6,4)
I believe the answer is:
ledger line
'staff' is the definition.
(thesaurus)
'brief note on account book' is the wordplay.
'brief note' becomes 'line' (I've seen this in another clue).
'on' says to put letters next to each other.
'account book' becomes 'ledger' (synonyms).
'line' after 'ledger' is 'LEDGER LINE'.
'showing addition to' 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?
(Another definition for ledger line that I've seen is " Stave addition".)