MM, the answer to 1 A is 7 letters and the answer to 9A is four. The top row becomes 13 letters long only because you use the letters at the beginning of 7 and 8 D to give you/reveal the thematic name. I assume it's the same for the one at the bottom. Once the two names are entered, all you need to do is work out what goes in the middle square - and I think there are hints on this thread for that (I'll check in a minute).