What lens is good to fit a nikon d750?

I'm getting a nikon d750 and I need a lens that will accommodate all my needs I will be taking semi professional portrait style pictures along with little landscape style pictures looking a lens that gets good depth of field and a clear photo

Semi professional? I'm not sure what this means. You are either a professional photographer (as soon as you charge a penny for your services) or a hobbyist. If you do not know what lens will do the work you require, you sure aren't ready to charge (that, and you obviously do not have the years of experience required and I doubt even a business license or liability insurance).

I don't do portraits, but I believe one of the 50mm Nikkor lenses would be recommended to you (I will leave that up to those who actually have this experience). Landscapes benefit greatly from wide angled lenses. I personally have a 14mm lens from a third party that is built to fit on Nikon bodies. If I had the money, I would love a Nikkor 14-24mm lens.

Depth of field and clarity come from not only the lens, but more importantly your settings on the body as well as post-processing. If you do not know what you are doing, you will see little or no improvement from cheaper DSLRs/lenses.

Be sure the lens you select works on a full frame camera. It should say in the description (Nikon usually puts FX on their full frame lenses vs DX for cropped sensor). Cropped lenses on a full frame body will cut a lot out of your image, making a full frame pointless.

This is a strange question for someone spending around $1500 or so for a camera body. You may find Nikon's cheaper DSLRs good enough for now.

For landscapes the Nikon 14-24 f/2.8
For portraits, the Nikon 70-200 f/2.8

You can go with Tamron's equivalents to save a lot of cash. To see how each compare, go to photozone.de where you can see just how sharp each lens is and therefore find a good lens for your needs.

If you haven't purchased the D750 yet, and aren't already invested in the Nikon system, then I would encourage you to go with Canon for portraiture. The Canon 70-200 f/2.8L is the best on the market. Nikon's version suffers from a good deal of focus breathing which means that at normal focusing distances, the lens may be at 200mm but in reality the optics are around 140mm. Plus, the Canon system has f/1.2 lenses that physically impossible to be designed for the Nikon system. Lastly, if there are specific Nikon lenses that you just have to have, you can adapt Nikon lenses to fit Canon DSLRs. However, you can't adapt Canon lenses to fit Nikon.

I use a 14-24 mm wide angle zoom for landscape photos and either a 24-70 mm f/2.8 or 85 mm f/1.4 lens for shooting portraits mounted on my Nikon D800e.

After you start learning the fundamentals of photography, you will see how your statement, " a lens that gets good depth of field and a clear photo" shows that you have some time ahead of you before you will be able to control depth of field and what it takes to get a "clear photo" (I'm assuming you mean tack sharp image)

Wide angle lenses will always produce more depth of field that longer lenses. When using a medium telephoto lens, then you will have more control if you need shallow depth of field.

You are getting an excellent camera, now you have to spend the time to learn how to use it to produce amazing photographs