It's possible to cleanly get the vocals from a beat and use the vocals, but I've never heard of someone getting the beat without the vocals cleanly.
You have to have one file of the song that has beat/vox and everything. Then you get another file of the song that is just beat. HOWEVER, the files have to be exactly identical in terms of file type (MP3, PCM, whatever) and in terms of quality (bitrate, 48k or 44.1... etc.). That right there is realllly hard to find sooo... yeah.
Then you put the tracks together in your DAW, zoooooommm wayyyyy in, and line them up 100% exactly right on. and invert the track that is just beat. This inversion will cancel out all of the audio in the normal track except for vocals. This is a legit method that would work on most songs, and it actually does get like 99.9% clean vocals. I've seen it done well.
The problem: It's nearly impossible to find identical files in terms of quality, and where one is an instrumental and one isn't. Plus, even if you do find files that way, they are probably mp3's and therefor not good to mix with because they are low quality.
I suppose you could use this method but the opposite way to get just the beat from a song, but I doubt you could find a 100% clean accapella version of the song to use to minus out the vocals from the normal track.
Anybody following me? lol. It could be done if you could actually find what you need to do it... but prolly not gonna happen.