What exactly is that part or what is it for? Sorry but unsure from that pix. Got one on your truck/buggy?
From just guessing (since not 100% sure what part it is
), it looks like a ball cup that might attach to a ball stud. Is that what it is?
Sometimes, the ball cup or stud will get worn. This will cause to much play, which will result in the ball cup easily popping off the stud. Not to much you can permanently do to fix this, except replacing the offending part.
One temporary "band-aid", is to apply a SMALL, thin piece of paper or foam inside of the cup. It will basically sit on the stud, and will tighten up the extra "play". This is of course, if that is the same part we are talking about.
Good luck