Peugeot 407 1.8 petrol. Good Car, smooth, 125k on clock.

Developed an issue this morning - when lifting foot completely off accelerator can hear a 'grating' kind of sound coming from engine bay i think.

Accelerate again and the noise disappears.

Wondering what it might be and if urgent ?

Also, is the clutch on the 407 cable or hydraulic - can the pedal & bite be adjusted ?

Any feedback appreciated.

Thanks in advance.

E