I'm in a bit of bother here! I have 10 extra words (49 letters in total!!) and completely stumped on 6 & 7 down. Also can't parse 27a and 13d. Finally, I have nonsense in the unclued lights. Other than that I'm doing OK.
Gitto - can't help on all of those but 6d is"A" followed by a 4-letter word for network test (there's a blank cell). 27a is the tonic sol-fa fo c, B & E (also with a blank cell).
By my reckoning there are 4 blank cells. I was wondering after my previous post whether 7d is an anagram of wash (giving a word which appeared a few weeks ago in 4859) but, if so, I can't make any sense of the rest of the clue.
There's nothing like posting for giving insight. Don't want to be too specific but in 7d IPA can stand for more than one thing and in this case you can't drink it!
Yes, I sorted 7d earlier, but it is a bit of a convoluted definition of the answer. I also don't think there is an extra word in 15a as I can sort of make some sense out of my first four and a half extra words, but then it all falls to pieces.