Possible Clues:

• Like a Keebler spokesman
• Sprightly
• Like storied North Pole workers
• Dainty morsel of mackerel, finely sliced
• Female in river swimming backwards can be rather delicate
• Mischievous and somewhat self-involved
• Impish fellow going into the river backwards
• Unruly Neil included fellow who was impish
• Sprightly in the end
• Sprightly fishy at finish