Clearing a location in fallout 4
If I clear a location in Fallout 4, it shows it as clear on map.
Does that location remain clear permanently?
If no, how does enemy spawning work in terms of time and difficulty.
Those locations do not stay clear permanently. For normal areas, it takes seven in-game days to reset. For "dungeons" (named quest-related locations that can be marked as "cleared"), it takes 20 in-game days (see this Reddit thread). These times scale with Survival difficulty — 35 in-game days for non-cleared areas, and 80 in-game days for cleared locations.