Crossword puzzle clue "almost inaccessible nest"

Almost inaccessible nest

Makes inaccessible

Inaccessible place

Try to get something inaccessible

Render inaccessible, as a nuclear waste containment unit maybe

Item: 1947 novel. Problem: Currently inaccessible; also probably sustaining fire damage.

When the entire Internet is inaccessible?

Accesses, as a previously inaccessible game level