You must have a short circuit somewhere. Doubt its anything to do with the stalk as the other side would blow too.

I've seen this before when someone put a screw through a cable, and also where the number plate light wire chafed as it was coming out of the back panel.

I'd dismantle the rear light unit and check the wiring, - also check the number plate light.

Something behind the dash could also be responsible - as the dash lighting circuit is also run of the same fuse. Have you fitted a new head unit or anything like that recently? You could also check the lighting cable for the cigarette lighter and the drivers side front side light.