The instrument (10) has an instrument head (11) comprising a movably supported nozzle (18) i.e. slim needle, and an actuator (23) arranged in the head and connected to the nozzle. The actuator comprises a fluid chamber (25), and a fluid conducting element (15) is provided in fluid communication with the chamber. The head is connected with an instrument connector body (12) via the conducting element. The nozzle is linearly supported such that the nozzle is movable along a jet direction (S) defined by the nozzle. The actuator is biased towards a retracted position by a spring unit (26). The instrument connector body is designed as a holding grip.
