Papal authority in Cavan, it disintegrated (7)
I believe the answer is:
vatican
'papal authority' is the definition.
(I've seen this before)
'cavan it disintegrated' is the wordplay.
'disintegrated' indicates an anagram.
'cavan'+'it'='cavanit'
'cavanit' anagrammed gives 'VATICAN'.
'in' is the link.
(Other definitions for vatican that I've seen before include "Residence of the Pope" , "ecclesiastical centre" , "Pope's residence" , "Papal palace" , "Palace of the popes in Rome" .)