On ours, there's only the clutchplate & retaining bolt (m6 I think), but the important thing is that there is also a washer inside the clutch plate nose - effectively a spacer between the clutch plate & shaft. The washer disappeared on ours when the clutch plate fell off.
On the s.h. compressor I bought, I initially didn't realise there was a washer because it was semi stuck inside the clutch plate nose by a bit of grease. It was only looking at some youtube videos I noticed there was one.
As long as you know to check it's there, replacement of the clutchplate, washer & bolt is easy (saving a lot of work needed to replace & re-gas a complete compressor)
You can see the washer etc in the attached Youtube video at about 2 mins 40s onwards.