I have a theory re 5a. I think that the setter had second thoughts about the answer and changed it but forgot to change the definition (or vice versa). "Ageist" would satisfy "announcement of just one summary" but I assume most folk - including me - put the answer which satisfies "reluctant".
I agree, much easier than previous weeks , and 20a made me chuckle
However, can someone please explain 18d, I have an answer that is a hidden, but I don’t understand the rest of the clue? It’s probably one of those obvious ones, but no PDM yet!