Robin Earl

While doing the weekly check under the bonnet, I have noticed that a thin rod emerging from thde general direction of the bulkhead has parted company with a "brass" slider / rocker attached to the rhs of the cylinder head. The plastic ball joint connecting the 2 components has snapped. What does this assembly do and is it o.k. to drive until I can get a new assemby from a Citroen dealer. Any thoughts or help much appreciated.