Cave in (4)
'cave in' is the definition.
(synonyms)
This is all the clue.
(Other definitions for collapse that I've seen before include "Give way, fail suddenly" , "Suddenly fall down or give way" , "Fall down or cave in" , "Fall down suddenly like escallop" , "Break-down or complete failure" .)
'cave in' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for give that I've seen before include "Yield to pressure" , "Yield, produce" , "To yield; resilience" , "Donate or hand over" , "Contribute - elasticity" .)