Thanks to both of you for your "noble" advice. As it happens I had the wrong answer "preface" meaning "introductory requirements". No wonder I could not parse it!
I am now in the right House.
Thanks Notrab, although I did make a slight error in parsing "for one" before "time" but, thankfully, Buzzybee showed them in the correct order and it doesn't appear that my error hindered you:-)
As an update to post #1, I was correct that this is Twin’s debut in the Guardian, but I’ve subsequently discovered that he has also set for the Listener and Magpie as Twin, as ‘Prime’ for the Telegraph Toughie and as ‘Agenor’ in the TLS.
To amplify that, Jono, Twin won the Ascot Gold Cup in 2020 and 2022 for the Listener puzzle voted best of the year by the all-correct solvers. This is quite a feat, and marks him among the elite
Not surprised that Twin has won prizes if all his/her puzzles are of this standard. NB: could all you clever cruciverbalists suggest a gender neutral pronoun, etc?
Well, I've almost finished and more or less understood it all (although the middle part of 25A being "Creature" seems rather contrived, if I've understood it). But, I am having problems with the last two, being 18D and 21A. Any hints, please?
19 -I + 4-letter word for passed inside 3-letter word for turf. 21 - move the comma: 4-letter word for others, 2-letters around being "discontented" was.