I would recommend remove the flywheel and retreive the punch. The broken piece could damage the magnets on the flywheel or damage the stator.
Either is a pretty expensive fix and a good puller can be had cheaper.
If you ever remove another clutch bolt, just remove a sparkplug and stuff a foot or so of recoil rope in there to lock the engine while you remove the bolt.
Then torque the bolt to 55 ft. lb. if it 7/16" when you reinstall the clutch.
Then remove the rope and reinstall the sparkplug. May have to turn the engine a bit to get the rope to come free.