You have the break in the right place. The definition is "Greek king". "One" becomes "An" and surrounds "game" and one of the three letter sequences. 13a is the name of a Roman orator.
Can anybody help with 3d? I have all the intersecting letters but can't make any sense of the clue. Is it the name of a particular Austrian valley, or a generic word for an alpine valley?
There seem to be more proper names in this puzzle than is usual. It took me a while to work out 39a, as I had never heard of him.