The clutch and it loses pressure?

Typically it's the clutch master cylinder causing the pedal not to return. I would recommend replacing both the clutch master cylinder and slave cylinder because both move together both have the same amount of use or wear. Usually what happens is you replace the clutch master cylinder only and the slave cylinder wears out faster because of the increased pressure produced from the new clutch master cylinder
Thanks for the question

It can be either, I would check for leakage at the rear of the clutch master and the front of the secondary cylinder. This will tell you where the fluid is going and replace that part and it should fix the problem.