English king upset large part of church before start of divorce is declined (8)
I believe the answer is:
relapsed
'is declined' is the definition.
(to relapse is to decline or get worse again)
'english king upset large part of church before start of divorce' is the wordplay.
'english king upset' becomes 're' (I am not sure about this - if you are sure you should believe this answer much more).
'large' becomes 'l'.
'part of church' becomes 'apse' (part of a church building).
'before' says to put letters next to each other.
'start of' suggests taking the first letters.
The first letter of 'divorce' is 'd'.
're'+'l'+'apse'+'d'='RELAPSED'
(Other definitions for relapsed that I've seen before include "Returned to former state, of illness or wicked ways" , "Suffered setback" , "Fell back (into sickness)" , "Weakened" , "Deteriorated in health again" .)