Conservative bishop entertained by old artist (9)
I believe the answer is:
constable
'artist' is the definition.
(painter John Constable)
'conservative bishop entertained by old' is the wordplay.
'conservative' becomes 'con' (abbreviation for Conservative).
'bishop' becomes 'B' (chess abbreviation).
'entertained by' means one lot of letters goes inside another (inserted letters are hosted or entertained).
'old' becomes 'stale' (similar in meaning).
'b' put inside 'stale' is 'stable'.
'con'+'stable'='CONSTABLE'
(Other definitions for constable that I've seen before include "in blue?" , "Bobby" , "He painted" , "CARRY ON FILM" , "Law enforcer" .)