pnp current limiter
A current sense resistor is obviously needed, unless you can rely on a only roughly known transistor current gain.
A simple circuit uses Vbe of an auxilary transistor as threshold, it has to accept e.g. 0.5 V voltage drop in normal operation. More complex circuits are sensing the current by a lower valued resistor and an OP or a current mirror.
You should also consider, if simple current limiting is appropriate, cause the output transistor must be able of handling high dissipated power permanently. Bistable electronic fuses are sensitive to inrush currents and also need a reset signal.