That hole is there to drain off a leak from either the rear main seal of the engine or the front seal on the transmission. There is also an inspection plate forward of that hole. (black plastic cover)
Can you tell what is leaking? engine oil or transmission. I'm not familiar with the standard transmission, so hopefully someone else can chime in with more specific info. Having any fluid back there where the clutch contacts the flywheel is not a condition you can over look.