13a is a shocker. Convoluted 15 word clue leading to a 16 letter word most people will never have heard of. Still don't understand 40d, what does 'cut capers' mean? This puzzle is also marred by other obscurities – aweto, iritis, illyria anyone?
27a Hertfordshire village a short way east of railway (7).
Elstree? 'Stree' is a short way, but where's the railway?
36d Grand mushrooms rising broad and flat, billions must be about (11)
Looks like 'spectacular'. I can see the 'mushrooms rising' in 'spec' but no more.