put a spanner in(to) the works

To disrupt, foil, or cause problems to a plan, activity, or project. Primarily heard in UK. We had everything in line for the party, but having the caterer cancel on us at the last minute really put a spanner in the works! It will really put a spanner into the works if the board decides not to increase our funding for this project.

put/throw a ˈspanner in the works

(British English) (American English throw a (ˈmonkey) ˈwrench in the works) (informal) spoil or prevent the success of somebody’s plan, idea, etc: Let’s get this finished before the boss comes along and throws a spanner in the works.

A spanner or wrench is a metal tool used for fastening things tightly. The works are the moving parts of a machine.