Sitting at a cafe on college campus brings back some good memories, though it's only been a little over a year since I left the days of torn sweatshirts and Ramen noodles behind!
Here is a photo of a singer in a very dimly lit cafe. Any comments and suggestions are very welcome.

The highlights in the window catches the eye and detracts from the singer. I am not sure if it is possible to tone them down? Would it be possible to fill the highlights with yellow or a similar colour thus matching the colours in the rest of the scene? It would give a better balance?

You're right Stamper! Difference in WB does detract a little, but I somehow like the idea of separating the inside from the outside by use of the varying WB. I did use an adjustment brush to bring down the exposure & saturation a little. I believe the only way to match inside/outside would be by using layers? I don't believe its possible in Lightroom... I've tried using the HSL tool, but that didn't really work as well.

Sayeed, It was a worthwhile try but I have to agree with Stamper. Without the window there's nothing left but a girl shouting. With the window the girl becomes secondary.

I would suggest trying to shoot from an angle where her hair doesn't obscure her eyes. She looks like she's passionate about her performance, but that message isn't reinforced by the passion in her eyes because we can't see them. It's a nice attempt, but unless you can capture a unique moment or composition, it just gets lost in the millions of other musician portraits.

What about some cropping? I think the girl has enough background elements around her to keep the mod, even if you crop the picture and leave the entire window out (or at least, get rid of a big part of if). Jut my two cents.