chafe at the bit

/CH EY1 F AE0 T DH AH0 B IH0 T/
verb
  1. 1

    To bite the bit, especially when restless

  2. 2

    (of a person) to show impatience or frustration when delayed

Source: https://en.wiktionary.org/wiki/chafe%20at%20the%20bit, https://en.wiktionary.org/wiki/champ%20at%20the%20bit