I don't like to argue with you, elle (or anyone!) but surely staple as a noun means the wire things, or as a verb means to hold things together with the bent wires. As far as I can see "steady" is an adjective which "staple" can't be. But you know far more about grammar than I do.
As I said, I think it is simply a mistake and Barnstaple is the answer. After all, there's another spelling mistake in the clues.