Simple things first. When the bike is parked, and it's quite, pull the clutch lever and release a few times. Do you hear a sound coming from the place where the front sprocket is? That would be the sound of the clutch rod moving back and forth.
If you don't hear any sound, the problem is likely with hydraulics. If you do hear the sound, the problem is likely with the clutch itself.
Any recent work done on the bike? What's the history of this problem - started happening suddenly, or gradually over time?