Capitalist's banking on old money that's obsolete (7)
I believe the answer is:
extinct
'that's obsolete' is the definition.
(I've seen this before)
'capitalist's banking on old money' is the wordplay.
I cannot quite understand how this works, but
'old' could be 'ex' (prefix meaning former or onetime) and 'ex' is found in the answer.
'money' could be 'tin' (old-fashioned slang term for money) and 'tin' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for extinct that I've seen before include "Like a dodo" , "gone for ever" , "No more vital" , "Ended" , "(Of a volcano) dead" .)