Extruder clogged?

After replacing PLA filament, it seems like something is blocked. I can see the filament go through the clear tube into the extruder part, but when I expect some filament to come out of the hotend, I hear a clicking sound.

What is the proper procedure to remove the clog?

Hi!
A while ago I also had these noises and problems with the filament flow.
On my device the FILAMENT PULLEY was no longer fixed on the stepper motor axis. For the movement of the filament, it has still been enough but no longer for extrusion.

greetings from Berlin
Steffen