What is Crumble ?
Crumble is (noun) a hot cooked dessert made of fruit covered with a mixture of flour, fat and sugar We are having apple crumble and custard for pudding.(verb) 1. to break something up into small pieces He picked up a lump of dry earth and crumbled it between his fingers. As the waves battered the cliff it began to crumble away. 2. to collapse As the witness said what he had seen, the defendant’s case crumbled. All her confidence began to crumble.
source: Easier English, Student Dictionary Upper Intermediate Level