Adjust pto air gap to .015 at clutch, three places, windows for feeler gauge. You will need to remove deck for access. Remove key from ignition and negative battery cable for safety’s sake.
Disconnect the PTO connection at th clutch. Then start the engine and engage the PTO. If the fuse blows, the clutch is good and you have a short somewhere in the wiring or PTO switch. If the fuse doesn’t blow you have a short in the clutch.