throw a spanner in the works

verb

verb

UK, Idiomatic To introduce a problem, dilemma or obstacle, something unexpected or troublesome.

Halfway through the production of Macbeth, the director found that the stage was smaller than he had expected. This really threw a spanner in the works.

Related terms: throw a wrench in the works, put a spoke in someone's wheel, monkey wrench, spanner in the works

Entry derived from the Wiktionary, under licence CC BY-SA 4.0 — list of authors.