Cardinal saves church with end of steeple in decline (6)
I believe the answer is:
recede
'decline' is the definition.
(both can mean to decrease or diminish)
'cardinal saves church with end of steeple' is the wordplay.
'cardinal' becomes 'red' (I've seen this in other clues).
'saves' indicates putting letters inside.
'church' becomes 'CE' (abbreviation for Church of England).
'with' means one lot of letters go next to another.
'end of' indicates one should take the final letters.
The last letter of 'steeple' is 'e'.
'red' placed around 'ce' is 'reced'.
'reced'+'e'='RECEDE'
'in' is the link.
(Other definitions for recede that I've seen before include "Start balding" , "Go backwards" , "Move backward" , "Go back, ebb" , "Decline" .)