A husband breaks vow in church state (5)
I believe the answer is:
idaho
'church state' is the definition.
'idaho' can be an answer for 'state' (US state). I am not sure about the 'church' bit.
'a husband breaks vow' is the wordplay.
'husband' becomes 'h' (abbreviation).
'breaks' means one lot of letters goes inside another (inserted letters break into the word).
'vow' becomes 'I do' (I do, marriage vow).
'a'+'h'='ah'
'ah' inserted into 'ido' is 'IDAHO'.
'in' is the link.
Can you help me to learn more?
(Other definitions for idaho that I've seen before include "US state in the Rocky Mountains" , "State of NW US" , "O, I had a change in this state" , "US location" , "American state, capital Boise (5)" .)