Possible Clues:

• 'Painting Hour' -- it's an inflammatory experience
• Stiffness of the joints
• Boy with no university, it is a joint problem
• The object is to support king dismissing united or joint complaint
• Disease of the joints
• Purge all extreme characters from party -- the British complaint
• Joint pain
• Possible confirmation of leader for Camelot, not united in joint complaint
• Without you, Arthur, so it is, is the big stiff with it