Thanks so much, Castafiore. So I needed a better dictionary for 6 and 7 ac (though I agree with you that if 6 is a themed solution, the first two words of the clue shouldn’t be there, and if it isn’t we are missing a themed solution as well as one of the 30!)
As for 48d, I was just being dense.
It would be a shame if the instructions proved to be defective in one respect (or arguably two respects), as it gives ammunition to the Maskaradophobes (much in evidence in this thread, both by the comments and by the absence of many of the usual posters), and it becomes more difficult for fans like me to fight the setter’s corner.