Related Clues:

• A problem that's difficult as second fiddle
• Really tough puzzle, say
• Problem for one with BO
• Some fishing equipment catching trout finally, a hard problem
• Unpleasant person — difficult task
• Scoundrel — rotten egg, perhaps?
• Second fiddle is one making a hum
• Small and naughty child is scoundrel
• Difficult task (informal)
• Puzzle that's more hard than fun, say
• Second fiddle? That's a difficult question
• Small toy, one that hums?
• Very difficult task (informal)
• Difficult question for bad egg, say?