keep cave

act as lookout

望风

caver in

(或cave something in)(with reference to a roof or similar structure) subside or collapse or cause something to do this

(屋顶等)下陷，坍塌，倒塌；使下陷，使倒塌

the ceiling caved in.

天花板塌了。

Len's club would have caved his skull in.

伦的棍子就已经把他脑袋打陷下去了。