Possible Clues:

• One of the 19 can get on in the hierarchy
• Moron
• Collection of writing with chapter by author unknown
• Continue to preserve an ecclesiastic
• See, say, unidentified writer's catalogue of principles
• Is the end of 6 down able to be in church?
• Basic law or principle
• Priest may be caught out soon
• Clergyman caught on immediately
• General principle; musical round