Possible Clues:

• Catchword
• Humour ultimately missing from sadly integral part of a joke?
• Something funny in setting of gelatin
• "One man's struggle to take it easy," for "Ferris Bueller"
• 'One man's struggle to take it easy,' for 'Ferris Bueller'
• Something funny, perhaps, left in stew
• 'Just when you thought it was safe to go back in the water,' e.g
• Entertainer's signature