Under the gun
Definition 1 of 2
Pro Tip 1/3Time Pressure
Use it to describe situations with tight deadlines and a need for quick action. 
I'm under the gun to submit my essay by tonight.
Pro Tip 2/3Work Stress
It's often used to express stress related to job tasks or responsibilities. 
She feels under the gun with the upcoming audit.
Pro Tip 3/3Emotional Weight
Conveys anxiety or stress emotions felt in high-pressure situations. 
Under the gun, his hands shook as he presented.