What is Clash ?
Clash is (noun) 1. a loud noise of metal things hitting each other She heard a loud clash like two saucepans being banged together. 2. a battle or an argument There were clashes outside the football ground between supporters of the two teams. We are getting reports of clashes between government forces and rebel groups. 3. the shock of two colours seen close together If you wear red tights with an orange dress there will be a colour clash. (NOTE: The plural is clashes.)(verb) 1. to bang things together making a loud noise She has to clash the cymbals at the end of the piece of music. 2. to argue violently She clashed with her mother about wearing a ring in her nose. The opposition deputies clashed with the government during the debate. 3. to fight Rioting fans clashed with the police. 4. to happen at the same time as something else The party clashes with a meeting I have to go to. Unfortunately, the two meetings clash, so I’ll have to miss one. 5. (of colours) to shock when put side by side That bright pink tie clashes with your green shirt.
source: Easier English, Student Dictionary Upper Intermediate Level