Started this late (yesterday.) By the way, if you look at the puzzle when it comes out, be sure to reread the preamble if you start much later. I could not get any of the perimeter, until I went back and saw wordplay only. Blonde moment.
So I'm about done now, but I can't parse 14. I filled in the message so I know the extra letter, and I see what the entry must be, but I can't see how. Any hints are welcome.