Friends quietly sliding down mountains (4)
I believe the answer is:
alps
'mountains' is the definition.
(alp is a kind of mountain)
'friends quietly sliding down' is the wordplay.
I cannot really see how this works, but
'quietly' could be 'p' (p for piano and quiet) and 'p' is located in the answer.
The remaining letters 'als' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for alps that I've seen before include "European mountain range" , "European mountains" , "Mountains in Central Europe" , "Mountain system in south-central Europe" , "Mont Blanc is therein" .)