Turning to steal from account, one gets caught, becomes penniless (7)
I believe the answer is:
boracic
'penniless' is the definition.
Although both the answer and definition are adjectives, I don't see how one could define the other.
'turning to steal from account one gets caught' is the wordplay.
'turning' says the letters should be written backwards.
'to steal from' becomes 'rob' (I've seen this before).
'account' becomes 'ac' (abbreviation for account).
'one gets caught' becomes 'ic' (I can't justify this - if you can you should believe this answer much more).
'rob' back-to-front is 'bor'.
'bor'+'ac'+'ic'='BORACIC'
'becomes' is the link.
Can you help me to learn more?
(Other definitions for boracic that I've seen before include "Acid used as a mild antiseptic" , "Poor Cockney" , "Broke" .)