Bad advanced Bishop advanced (6)
I believe the answer is:
addled
'bad' is the definition.
Both the answer and definition are adjectives. Maybe there's an association between them I don't understand?
'advanced bishop advanced' is the wordplay.
'advanced' becomes 'a' (abbreviation).
'bishop' becomes 'DD' (DD stands for Doctor of Divinity).
'advanced' becomes 'led' (I can't justify this - if you can you should believe this answer much more).
'a'+'dd'+'led'='ADDLED'
Can you help me to learn more?
(Other definitions for addled that I've seen before include "Gone bad (of eggs)" , "Rotten; muddled" , "Confused like infertile egg" , "mixed-up" , "Of egg, rotten and producing no chick" .)