Decline to discourage start of Irish pontificate (11)
I believe the answer is:
deteriorate
'decline' is the definition.
(deteriorating is a kind of declining)
'discourage start of irish pontificate' is the wordplay.
'discourage' becomes 'deter' ('deter' can be a synonym of 'discourage').
'start of' says to take the initial letters.
'pontificate' becomes 'orate' (I've seen this before).
The first letter of 'irish' is 'i'.
'deter'+'i'+'orate'='DETERIORATE'
'to' is the link.
(Other definitions for deteriorate that I've seen before include "Slip" , "Become steadily worse" , "Grow worse" , "Get worse" , "Fail" .)