when the wolf is at the door you are starving, the outside is coming in and your security is gone
If a hungry wolf is at your door, you are in serious trouble. Trouble has come calling. The "wolf at the door" refers to any danger or predator that seeks to ravage the inhabitants within, ranging from starvation and poverty to physical death.
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"Wolf at the door" is an idiom referring to hunger, so if you
drive the wolf away, you're keeping yourself from starving.