Hi Geeker,
Re 10a, I think the term used to create the answer is fairly universal in English speaking countries, and Chambers just gives it as an "informal adjective".
I chose it as a potential COD because I like the way an instruction for one part of the clue gives the answer.
Thanks for the Mose Allison reference. I'd never heard of him but just went to Youtube and listened to Young Man's Blues - loved it:-)