Where one might find bishop had claret prepared (9)
I believe the answer is:
cathedral
'where one might find bishop' is the definition.
(bishops work in cathedrals)
'had claret prepared' is the wordplay.
'prepared' indicates an anagram.
'had'+'claret'='hadclaret'
'hadclaret' is an anagram of 'CATHEDRAL'.
(Other definitions for cathedral that I've seen before include "Main church of diocese" , "Halted car, badly, at the important church" , "edifice" , "Principle church of diocese" , "See building" .)