Curious

[2 of the left]

Experiencing a single knock sound when depressing and releasing clutch pedal in my pfl Blue

[Gaz mr-s]

I haven't heard of a knock, but a squeak from the actuation fork is very common. It sounds as is it's inside the car until able to hear it from outside. Not sure if a dry release bearing could produce a 'knock'.

[2 of the left]

On closer inspection depressing by hand produces no sound but when activated by foot the knock returns

[Joesson]

@2 of the left
There is mention of a clutch related "knock" on the www, typically a release bearing is mentioned.
Even curiouser that it is not there when depressing by hand, not the easiest of operations!
Some time ago I experienced a similar strange noise and it turned out that the sole of my shoe had split and that was what the noise was.