Oil in the clutch?

Hi, did anyone had any experience in oil leaking into the bellhousing and making the clutch slip? if so what can be done?

very rare ,not oil leak but it contaminating clutch ,usual leak is rear main oil sea,and around main brg cap,300 tdi ali housing holding seal can warp making gasket leak l,they mostly all leak to more or less extent,but runs down rear of flywheel and out of wading plug ,which is best left removed till needed, clutch is probably just worn out