"Lion Hunter" is a slang term that I first read in Thomas Wolfe's novel You Can't Go Home Again. Since I had not heard it before, I assumed that it was either Wolf's invention or something used only amongst a small group. However, later I read the same term used in William Somerset Maugham's novel The Moon and Sixpence. Since Maugham wrote in a slightly different time and place than Wolf, I concluded that this must have been a fairly widespread piece of early 20th century slang that we have sadly lost.
A Lion Hunter is a woman who collects the presence of artists for purposes of social climbing. The artists are the lions, and the woman is the hunter. From the two novels where I read the term, the hunting is done solely for the purposes of conventional social climbing, and does not mean forming romantic relationships with such men. However, if it was a popular slang term, so long ago, it may have had many shades of meaning that are not recorded.
In any case, it is somewhat of a shame that it is lost, because I certainly have met many people that I would file under the heading of "Lion Hunter", and there is no longer a widely used term to describe them.