Really struggling here although I only have four unsolved clues. I also have the thematic title. It's filling the grid that is the problem. Finally, may I ask if the abbreviation is longer than 5 letters because that is worrying me.
I did guess where the name might start, but doing that, from the answers I have, gives me 2 down beginning with G, and nothing fits. I have no idea what the unclued entries are, but at least the name of the creator is 34 letters in total.