Observe the diocese (3)
I believe the answer is:
see
This clue is a double definition.
'observe' is the first definition.
(observe can mean to see something)
'diocese' is the second definition.
(I know that see is a type of diocese)
'the' is the link.
(Other definitions for see that I've seen before include "Bishop's seat" , "twig" , "responsibility of a bishop" , "ecclesiastical division" , "A bishop's district" .)