a tall order
Meaning: If you say something's a tall order, you mean that it'll be hard to do or difficult to achieve.
- Winning six gold medals at the Olympic Games is a tall order, but not impossible. Mark Spitz won seven at the 1972 Olympics.
- Getting kids to read 600-page books is a tall order these days, but the writer of the Harry Potter books has managed to do it.
We told the boss we'd do our best, but it's a tall order to