get/have cold feet
get cold feet
To experience nervousness or anxiety before one attempts to do something. I wasn't nervous until the morning of my wedding, but everyone assured me that I had just gotten cold feet. Good luck getting her out on stage—she always gets cold feet before a performance.
get cold feetor
have cold feet
COMMON If you get cold feet or have cold feet about something you have planned to do, you become nervous about it and not sure that you want to do it. My boyfriend got cold feet about being in a committed relationship. Leaving Ireland wasn't easy and I had cold feet about it a couple of times.