Definitely not a die break. That would be a break on the die itself. So when it strikes the blank planchet it would appear raised on the surface of the Nickel. And that is not a Die Clash. It looks incused into the field so it could be a struck through debris issue.
Does the design you see on the obverse look like any part of the design on the reverse? I doubt it so I’m thinking a struck through.
Depends on whether, if the area is raised or recessed, no? Looks like a scratch if you ask me. Better fully images please. The jury is out now.