Recover from cleric having religious books, say, in retirement (3,4)
I believe the answer is:
get over
'recover from' is the definition.
(I've seen this in another clue)
'cleric having religious books say in retirement' is the wordplay.
'cleric' becomes 'Rev' (abbreviation for Reverend).
'having' says to put letters next to each other.
'religious books' becomes 'OT' (Old Testament).
'say' becomes 'eg' (both can mean 'for example').
'in retirement' says the letters should be written backwards (retire can mean to go back or backwards).
'rev'+'ot'+'eg'='revoteg'
'revoteg' back-to-front is 'GET OVER'.
(Other definitions for get over that I've seen before include "Recover" , "Clear" , "master?" , "Deal with successfully, improve in health" .)