Rulers possessed by evil but making lots of money (8)
I believe the answer is:
killings
'making lots of money' is the definition.
I can't tell whether this defines the answer.
'rulers possessed by evil' is the wordplay.
'rulers' becomes 'kings' (king is a kind of ruler).
'possessed by' means one lot of letters goes inside another.
'evil' becomes 'ill' (as in doing people ill).
'kings' enclosing 'ill' is 'KILLINGS'.
'but' acts as a link.
Can you help me to learn more?
(Another definition for killings that I've seen is " Crimes".)