Clergyman giving approval? Withdrawing it? (8)

I believe the answer is:

revoking

I'm a little stuck... Click here to teach me more about this clue!

'approval? withdrawing it?' is the definition.
I can't tell whether this definition defines the answer.

'clergyman giving' is the wordplay.
'clergyman' becomes 'rev' (I've seen this before).
'giving' becomes 'oking' (I can't explain this - if you can you should believe this answer much more).
'rev'+'oking'='REVOKING'

Can you help me to learn more?

(Another definition for revoking that I've seen is " withdrawing".)

I've seen this clue in The Times.

Want a hint initially instead of a full solution? Install my app