I've got the screaming whatsits at 1D, so I assume I've got my quarters in the right place. According to my dictionary 19D is two words, so I don't know why the setter didn't say so (as with the clue in the 4d group)
Trouble is, I've assembled the misprints in the clues and I know where the final misprint is. There is then an obvious candidate for the ODQ reference - but I can't for the life of me see how this helps with filling in the final four squares. And if there are any subtle hints in this thread to date, I can't spot them either . . . can somebody please help?