Could be the clutch master cylinder. That's the easiest and cheapest bit to replace.
If it's the slave cylinder then do the clutch as well, as the cylinder's located inside the bell housing. Long (and expensive) job if it is that one, I'm afraid: front subframe off, rear prop and front driveshafts off, IRD off before you can even consider taking the gearbox out.
I'd get a proper diagnosis done if I were you and make your decision on that basis.