Thanks, Brendan, all done and dusted. I'd thought of Cleo's nemesis, especially as I had the last letter, but didn't work out how to combine it with the "Terminally Cleopatra" letter.
LOI: 9a. (Obvious, once I had 3 crossers and a hint!)
For 6d I had the last 6 letters, guessed Olympian as "god", googled the resulting wrong invented surname and found the right chap. I'd guessed the "6" element but for a while thought of the game Go", which didn't help.
Phew, hard work even with forum help, but got there eventually, and it's only Monday.
Thanks for your help, to all concerned.