Wouldn't be the clutch pushrod seal(s) - if that/they was/were leaking, oil would be dripping from the weep hole at the bottom of the bellhousing area.
Most likely it's the o-ring on the outer body of the throw-out bearing, or a cracked u-joint boot. The o-ring can be replaced by detaching the clutch cable, removing the cotter pin securing the clutch arm pivot pin, removing the clutch arm pivot pin and clutch arm. Then you can grab the outer body with pliers and pull it out of the transmission. Replace the o-ring and "reassembly is the reverse of disassembly".
To replace the u-joint boot with the proper one-piece boot will require the swingarm be removed.