To be kept on tenterhooks is to be held in a state of nervous apprehension: “We've been on tenterhooks since the election results started coming in.”
Note: A tenterhook was a hooked device used in the 1700s to secure newly woven cloth onto a frame.
In a state of painful suspense, as in We were on tenterhooks all through the game, hoping against hope that our team would win. This expression alludes to hooks that formerly were used to hold newly woven cloth that was being stretched on a frame. Their name has long survived this method of manufacture. [Mid-1700s]