Hi PS
I did get 18ac from your hint and the last letter led me to the famous sequencer. I also got 16d, though it isn't green food.
Thanks for the hint on 24d. Why didn't I think of that? Doh!
Are my letters right for 5ac - I can't parse it - F?R?E?S
Similarly, does 23d start with a B? If so what is the definition?
One more bash before I give up. I won't get time to do much tomorrow as I'm back to Budleigh for two more authors. I especially enjoyed Tim Harford yesterday.