Isn’t upset over a new church, for example (8)
I believe the answer is:
instance
'example' is the definition.
(I know that example can be written as instance)
'isn't upset over a new church' is the wordplay.
'upset' is an anagram indicator.
'over' means one lot of letters go next to another (in a down clue, some letters go over others).
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'church' becomes 'CE' (Church of England).
'isnt' with letters rearranged gives 'inst'.
'inst'+'a'+'n'+'ce'='INSTANCE'
'for' is the link.
(Other definitions for instance that I've seen before include "Case - isn't acne (anag)" , "Case in point" , "'Example, illustration (8)'" , "Occasion" , "Case or example from ancients" .)