Church is replacing contents of sanctum, hence division (6)
I believe the answer is:
schism
'church' is the definition.
(thesaurus)
'replacing contents of sanctum hence division' is the wordplay.
I cannot really understand how this works, but
'contents' could be 'his' (hi is a kind of content) and 'his' is present in the answer.
This explanation may well be incorrect...
'is' acts as a link.
Can you help me to learn more?
(Other definitions for schism that I've seen before include "Splinter group" , "Formal split in a church" , "Split, often ecclesiastical" , "Dividing of group into opposing factions" , "(Ecclesiastical) division" .)