| Answer | Crossword Clue |
|---|---|
| POSER | Hard problem |
| NUT | Hard problem. |
| TOUGHNUTTOCRACK | Hard problem |
| KNOT | Hard-to-solve problem |
| nut | hard problem or undertaking |
| ACNE | Problem that's hard to face? |
| ITCH | Hard-to-reach problem, at times |
| DEEP | Hard to understand, as a math problem |
| HAIRY | Hard to deal with, as a problem |
| stumping | (of a question or problem) Be too hard for; baffle |
| brain | to try very hard to understand and work out a problem, remember something, etc. |
