UP IN THE AIR means ‘undecided’.
Who gets the contract is up in the air.
The winner of the election is up in the air.
There was talk about having a meeting but things were left up in the air.
UP A TREE means to ‘be in a difficult situation’.
We have no money left for the month. We are up a tree.
If the insurance company doesn’t pay me, I will be up a tree.
He was caught trying to steal a company laptop and was up a tree.
UP TO PAR means ‘to be of the required standard’.
I am afraid your recent work has not been up to par.
I am not feeling up to par today. I must be getting a cold.
Are your computer skills up to par for the job?
UPSET THE APPLE CART means ‘to mess things up’. (I cheated – this is not an UP expression. 😉 )
I don’t want him on my team. He will upset the apple cart.
He upset the apple cart by telling everyone the confidential information.
There’s no need to upset the apple cart yet. Keep this information to yourself.