Employer around the old city was a loan-shark (6)
I believe the answer is:
usurer
'a loan-shark' is the definition.
(I've seen this before)
'employer around the old city' is the wordplay.
'employer' becomes 'user' (someone who employs or uses something).
'around' indicates putting letters inside.
'the old city' becomes 'ur' (ancient Sumerian city state).
'user' placed around 'ur' is 'USURER'.
'was' acts as a link.
(Other definitions for usurer that I've seen before include "Unscrupulous lender" , "One who charges undue interest" , "Lender who charges exorbitant interest rates" , "Businessman taking a lot of interest" , "source of interest" .)