Sorry, I had replied last evening but for some reason my reply didn't post. Here is a link to the parts diagrams for the various clutch housing and clutch assemblies for that tractor. There were a few different ones:2120 Clutch Housing & Clutch w/12x4 North America 1987-2/892120 Clutch Housing & Clutch w/12x4 North America 3/89 and up. After S/N UV322352120 Clutch Housing & Clutch w/12x4 Europe2120 Clutch Housing & Clutch w/HSS
All of them appear to have the same part number for the clutch shaft bushing, SBA398510010 (labeled as number 2 in each of the diagrams), which is what you would need to replace if it is leaking around the clutch shaft, in which case you will need to split the tractor to replace them.
But from your pictures, it looks like it might be leaking around part 6, which is part number SBA398110760 in all of the diagrams, and is simply called a rubber cover, which looks like it is just pressed into the hole, in which case you should just be able to replace them.
It also looks to me like the clutch housing is supposed to be dry inside, but I may be wrong. But if it is supposed to be dry in there, you've got a leak into the clutch housing from either the rear of the engine or the front of the transmission, in which case you'll need to split the tractor to address that leak.