A lot of money to get a piece of music? (7)
I believe the answer is:
'a lot of money' is the definition.
(I've seen this before)
'to get a piece of music?' is the wordplay.
'to get' becomes 'for' (as in 'to go shopping for presents').
'a piece of music?' becomes 'tune' (a tune is a piece of music).
(Other definitions for fortune that I've seen before include "'Chance, luck (7)'" , "Fate, destiny" , "large sum of money" , "Fate; riches" , "Luck; fate" .)