Be sorry about unrising income (7)
I believe the answer is:
revenue
'income' is the definition.
(I know that income can be written as revenue)
'be sorry about unrising' is the wordplay.
'be sorry' becomes 'rue' (I've seen this before).
'about' means one lot of letters goes inside another.
'unrising' becomes 'even' (I can't justify this - if you can you should give a lot more credence to this answer).
'rue' going around 'even' is 'REVENUE'.
Can you help me to learn more?
(Other definitions for revenue that I've seen before include "Income from tax" , "Money coming in" , "Takings" , "profit" , "Money received" .)