tall order
large order

Trying to change both practice and culture in the City is a tall order.

To be sure, she has taken on a tall order.

To find that line would have been a tall order.

That's a tall order, but talk to your health care team for support.

But this is a very tall order, and a lot of things could go wrong here.

He looked at me like that might be a tall order.

Given the data on training, though, this may be a tall order.

The second goal so quickly after the first made it a tall order to get back into the game.

Even for a company with such a fine safety record, this is a tall order.

That is a tall order. It will not be easy.