A Catholic place of business, a large one in the Vatican (7)
I believe the answer is:
archive
'business a large one in the vatican' is the definition.
I can't judge whether this definition defines the answer.
'a catholic place' is the wordplay.
'catholic' becomes 'RC' (abbreviation for Roman Catholic).
'place' becomes 'hive' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'a'+'rc'+'hive'='ARCHIVE'
'of' is the link.
Can you help me to learn more?
(Other definitions for archive that I've seen before include "File away" , "Record, annal" , "Save data for storage" , "Document depository" , "Records or historical papers of an institution" .)