What is the X here?--I'm on a X for time

I’m trying to say I have "less time" these days. I heard my english teacher use a sentence like: "I’m on a crutch for time" and I understood from context that it means they lack time. But years later when I googled that, it’s invalid. Is there a filler word that makes the sentence correct? I’m on a X for time. What X works to accurately represent that I lack time?