After musical work not completed, advanced money, being rich (7)
I believe the answer is:
opulent
'rich' is the definition.
(similar in meaning)
'after musical work not completed advanced money' is the wordplay.
'after' means one lot of letters go next to another.
'musical work' becomes 'op' (abbreviation for opus).
'not completed' becomes 'u' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'advanced money' becomes 'lent' (I've seen this in another clue).
'op' next to 'u' is 'opu'.
'opu'+'lent'='OPULENT'
'being' acts as a link.
Can you help me to learn more?
(Other definitions for opulent that I've seen before include "Well-to-do, rich" , "Let up on, being wealthy" , "Prosperous" , "Ostentatiously costly and luxurious" , "Ritzy" .)