I've finished and a clever puzzle indeed, although some of the wordplay seems wrong to me and I didn't bother checking the missing and extra letters for completeness.
Glad you're finished, glad you too thought it was clever, Orson. I think all my extra letters are fine, but I didn't get the point of the missing ones! As I don't parse everything, I haven't got any quibbles with any of the wordplay.
For what it's worth, (I know you're not as 5d. as myself malone) but the single letter omissions do exactly as it states in the preamble; completes the "set".
Thanks Malone for your earlier post. I realised I was wrong but it’s hard to type as I’m flat on my back in bed a bit I’ll. I loved this puzzle very much.
Thanks again to everyone.
Thanks for that, Jogamel. Glad you finished and loved the puzzle. Hope you're on the mend soon (that's if you didn't take to your bed yesterday to avoid ... Inquisitor 1588?!)
Slugabed, your letters are correct. It's a thematic entry, the answer itself is longer. The definition is 'puzzle', verb. The last part of the word is 4 letters, used often in maths/arithmetic. The first part of the word is the 'not'.