Agreed re 3dn, although your first thought hadn’t occurred to me until you mentioned it. It works though, and I’ll be interested to see what Paul’s solution is. Black mark for him anyway.
Re 1ac: I think it parses as (what make up) a dog’s coat on the outside, with ‘one’ following its first letter, then a colloquial word (usually a verb) for an essential surrounding the opening of ‘position’.