A shot in the locker old-fashioned noun phrase
Having only one chance left one can do in order to achieve something
This is a shot in the locker. I can't screw it up.
It's very intense right now! Peter has a shot in the locker.
Don't lose hope! You still have a shot in the locker before everything goes south.
The last opportunity for one to achieve something
To be very wet
Because of forgetting bringing an umbrella, I look like a drowned rat when it rains.