Employer in old city around southeast (4)
I believe the answer is:
user
'employer' is the definition.
(thesaurus)
'old city around southeast' is the wordplay.
'old city' becomes 'ur' (ancient city state).
'around' means one lot of letters goes inside another.
'southeast' becomes 'se' ('SE' can be a synonym of 'southeast').
'ur' enclosing 'se' is 'USER'.
'in' is the link.
(Other definitions for user that I've seen before include "Manipulator" , "One who employs" , "Ruse (anag.)" , "junkie" , "Operator (of something)" .)