cave in

(noun) the sudden collapse of something into a hollow beneath it. Synonyms: cave in, subsidence.

(verb) break down, literally or metaphorically. Synonyms: collapse, fall in, cave in, give, give way, break, founder. Examples: "The wall collapsed." "The business collapsed." "The dam broke." "The roof collapsed." "The wall gave in." "The roof finally gave under the weight of the ice."