It was filmed anywhere between the very late 40's to the late 50's, possibly very early 60's (but I don't think so). It's based around about 5 women, somewhat high in society, one of whom is a singer/actress (I though she was played by Rosemary Clooney, but I think I'm wrong) and she's battling with the fact that she's no longer a young starlet. Her marriage is also failing, and he has a gold-digging girlfriend on the side. The gold-digger (I thought she was played by Elizabeth Taylor, but I think I'm wrong about that, too) also has a few other men on the side. I remember in the end, the gold-digger is confronted by the other women, they call her out, and they they kill the idea in her head that the husband is going to leave his wife for her. I wish I could think of anything else, but I can't. I ask because I can't think of the musical number performed by the singer in the latter half of the film.

You know -it's not an exact match, but my first thought was this:
All About Eve - Wikipedia, the free encyclopedia

No, but thanks. I keep thinking "The Women", but I know the one I'm trying to think of is in color.

Hmmm... there is a made for TV movie called 'Applause', came out in 1973 - it's a version of the broadway musical of the same name, based off All About Eve (I'm still stuck on that!) You mentioned youre looking for a musical number that was in the film, this movie, being based off a musical, might be it... ) I could only find someone's taping of the TV broadcast on you tube (like someone actually videotaped the TV while it was playing the show, maybe it will ring a bell?)Applause (TV Movie 1973) - IMDbhttps://www.youtube.com/watch?v=HPdyohUhieE

That's not it either, but thank you.

Hmmm... there is a made for TV movie called 'Applause'

It was “The Opposite Sex”. I mistook Joan Collins for Elizabeth Taylor