The assembly is the clutch slave cylinder.... Again it is not oil unless it is leaking out of the bottom of the tranny and that could be a main seal.... There is no possibility of oil coming out that hole because thats where the flywheel and clutch sit...
Soon enough if it is clutch fluid you will leak out all of it and you will ahve no clutch
So go buy a manual for the car and figure out how to A- either fix it, or B- what the problem is and take it somewhere to fix it.