Feel sure I'm going to kick myself, but stuck on 23d Clue to sage being at an improved stage of development? (6-10)
I have so many letters and no answer
?e?o?f-?e?e?a?i?n
Thanks Brackendale. I thought my inability to parse this might be too many late nights, but
in fact the clue was just too subtle for my old brain. Happy New Year.