An electrosurgical instrument including a protective tube, to be inserted into a working channel of an endoscope, and an electrode disposed within the protective tube. The electrode is movable in a distal direction and a proximal direction inside the protective tube by a control element. By being moved in the distal direction, the electrode can be brought into a deployed position in which the electrode at least partially protrudes from a distal end of the protective tube. The distal end of the protective tube has a closure element with an opening for the passage of the electrode. The opening of the closure element has a maximum internal diameter smaller than the internal diameter of the protective tube and is used for guiding and/or cleaning the electrode.