I must be really dense (or merely completely ignorant of the theme). I've solved all the normal clues, found the 16-letter message, googled it to find the rhyme. I can even work out what most of the 7 shaded words are. I've solved one (the last across) of the "other" clues, but it seems to have no connection with the only word which fits the space. Can some hip solver nudge an old man in the right direction please?