Revelation is boring for a clergyman (6)
I believe the answer is:
oracle
'revelation' is the definition.
(I have seen 'Divine revelation ' mean 'oracle' so perhaps 'revelation' could also mean 'oracle')
'boring for a clergyman' is the wordplay.
'boring' indicates the answer is hidden within the clue (the solution has bored or cut into the clue).
'ORACLE' is hidden within 'for a clergyman'.
'is' acts as a link.
(Other definitions for oracle that I've seen before include "Wise utterance" , "Source of wisdom, prophet" , "Source of divine prophecy" , "Shrine; its message" , "Divinely-inspired prophecy" .)