Possible Clues:

• Crossword clue, at times
• A play on words, perhaps the lowest form of wit
• 'Queen of denial,' e.g.
• It may elicit groans
• Crux of some riddles
• "Treat homonyms as synonyms": Walter Redfern
• A play on words, not really wit
• Wit's end?
• Ogden Nash bit
• Cause of a smile, maybe