Enjoyable today despite a complete brain freeze on several.
Couldn’t agree more with 23a. I too felt “mustn’t” is an order whereas the answer is something which is optional. Same ballpark, definitely, but synonymous? I’m not sure.
I note this setter is happy to use apostrophe phrases and in general I quite like them (“ps and qs” the other week was also fun).
4d was brilliant and reminded me of one of my favourite cryptic clues... geg? (9,3) ... albeit that’s more of a breakfast item than a sweet.