1-check primary fluid level to ascertain NOT over-filled. service and owners manual cover checking of same.
2-primary end of clutch cable is a VERY DELICATE threaded barrel with an O-RING affixed to same. the O-ring is the source of your leak.
after performing step #1 take a small open-end wrench and check that the cable is snug at the primary cover end. notice i said SNUG. many an XB owner has destroyed barrel threads, cables, broken off fittings, and other assorted carnage with ham-fisted work in this cable area. if these steps don't resolve the misting of oil from this area the cable will have to be removed and the O-ring replaced.
i'll tell you right up front that completely removing the cable, cleaning and lubing, and replacing the o-ring is not only tedious and challenging for the novice....there is only ONE method of doing it correctly. failure to adhere to same yields nightmare results.