Longman Dictionary of Contemporary English - spanner

~ n 1 BrE a metal tool that fits over a nut (nut1 (2)) and is used for turning it to make it tight or to undo it; wrench2 (3) AmE  (- see also ring spanner) 2 put/throw a spanner in the works BrE informal to unexpectedly do something that prevents a plan or process from continuing or succeeding  (He won't lend us the money? Well, that really puts a spanner in the works.)