Country to study old money (7)
I believe the answer is:
denmark
'country' is the definition.
(I know that Denmark is a country)
'study old money' is the wordplay.
'study' becomes 'den' (term for a study or office).
'old money' becomes 'mark' (I've seen this before).
'den'+'mark'='DENMARK'
'to' is the link.
(Other definitions for denmark that I've seen before include "Ditto" , "kingdom" , "Mark end of the country" , "Aarhus is its second-largest city" , "EU member" .)