Definition of a wrench in the works in English:

a wrench in the works

(also a monkey wrench in the works) (British a spanner in the works)

phrase

  • A person or thing that prevents the successful implementation of a plan.

    ‘he has thrown a wrench in the works by saying he would prefer direct elections to happen’
    • ‘a cancellation can throw a real monkey wrench into the schedule’
    interfere, interfere with, hinder, hamper, obstruct, disrupt, impede, inhibit, retard, balk, thwart, foil, curb, delay, set back, slow down, hold back, hold up