Bishop philosophical, with pillock beginning to evangelise in diocese (8)
I believe the answer is:
berkeley
'bishop' is the definition.
(Berkeley is an example)
'pillock beginning to evangelise in diocese' is the wordplay.
'pillock' becomes 'berk' (I am not sure about this - if you are sure you should believe this answer much more).
'beginning to' indicates taking the first letters.
'in' is an insertion indicator.
'diocese' becomes 'ely' (I've seen this before).
The first letter of 'evangelise' is 'e'.
'e' inserted within 'ely' is 'eley'.
'berk'+'eley'='BERKELEY'
'philosophical with' acts as a link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for berkeley that I've seen before include "Thinking bishop" , "American university" , "US University" , "Busby -, twetieth century director of film musicals" , "Calif. university; Irish philosopher" .)