RobP86 1d the spare letter arises from the anagram (new) of age. I think the spare in 38a is half of 'morning' - usual abbrev.
Got there in the end having worked out the author, then the book and quote. Still not completely clear on some eg 21a got the answer, know the spare letter but?? Same thing with 27a and 39a...how on earth is their a c involved?!
Still, quite pleased.