Amount owed by retired artist rises (7)
I believe the answer is:
arrears
'amount owed' is the definition.
'by retired artist rises' is the wordplay.
'by' says to put letters next to each other.
'retired' says the letters should be written backwards.
'artist' becomes 'ra' (Royal Academician, member of Royal Academy of Arts).
'rises' becomes 'rears' (rearing is a kind of rising**).
'ra' back-to-front is 'ar'.
'ar'+'rears' is 'ARREARS'.
(Other definitions for arrears that I've seen before include "Total unpaid debt" , "Amount needed to be paid back" , "Amount unpaid" , "If in these, the money is overdue" , "Back payments due on a debt" .)