on tenterhooks, in a state of uneasy suspense or painful anxiety: The movie keeps one on tenterhooks until the very last moment.
Origin of tenterhook
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
one of a series of hooks or bent nails used to hold cloth stretched on a tenter
on tenterhooks in a state of tension or suspense
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012