Clutch thrust or throw out bearing.
This is its purpose in life explained
https://youtu.be/o8SNwgvLpg8
Mine sounds bad, it sounds like a chattering sound coming from the front of the manual gearbox with the clutch out and not in gear.
Here is my Jeep, skip to 10:10 to hear what mine sounds like
https://youtu.be/Zf71CO8345M
And here is the solution breakdown, this guy explains it really very well.
https://youtu.be/Ifx3x_7w5BY
Just thought I'd post this on here for future reference and the benefit of others.