Thanks Chris for your explanation. That's what I thought. Meanwhile I retreated to our west facing sitting room and promptly fell asleep. It has been a busy week. I think I may give up soon.
But first I must tell you all of the magnificent garden I went to on Thursday with my U3A group. If you are in Devon, then please consider visiting Burrow Farm Gardens, near Axminster. Free to RHS members on a Friday. Admittedly, it was a lovely day, but the gardens were lovely too and we ended the day at the tea rooms where tea/coffee and cakes were in abundance. They sell plants too.
That's my excuse for not getting on with the crossword this week.
I've got a glass of wine and I'll see if that brings any elucidation.
What about a hint for 13d