Ixion - you were right about the word count at 17ac being a typo. It's just been corrected on the site. Doesn't help though. I know the 'answer', but not how to enter it. Is there a recognisable pattern?
The letter count for 17ac has now been corrected to (4,6) on the site.
All the other letter counts for the 5 26downs show the number of letters in the grid (ie after a letter has been removed from the answer.)
Ixion - I wouldn't have got 17ac without your help - thank you. I was trying to make an anagram of the right letters, but none of the anagram sites I use recognised it. I'd certainly never heard of it. So thanks again. All finished and submitted now.