### Clue: Knock back drink in old church and head for bishop's office (10)
### Answer: EPISCOPATE 
 ### Explanation: Definition: bishop's office
 **Reversal of**(Knock back) {[SIP(to drink with small mouthfuls) **contained in**(in) [O(abbrev. for "old") + CE(abbrev. for the Church of England)]} **plus**(and) PATE(a person's head).