[JSPERFORMANCE]

The clutch is not completely disengaging(sp).
The problem could be hydraulics that need to be bled, a misaligned clutch fork/throwout bearing, bad slave or master cyl, or recently I have found that when the flywheel gets cut it can affect the throw of the throwout to the point that complete disengadgement becomes an issue. These issues are the most likely cluprits, the clutch itself would be very low on my list of suspects and only condemned after the previous things have been checked..

Give the mechanic a chance to go over his work and fix the problem, if he insists that the clutch is at fault without at least re-checking and re-bleeding the system than you may want to go elsewhere before you buy a new clutch.