The most common and most likely answer to this crossword clue is the 5 letter word SCREE
I've seen this crossword clue in Independent
S
C
R
E
E
More clues leading to the result SCREE
- Endlessly sift loose pieces of rock
- . Discover chromium in rockfall
- Southern Native American rock formation
- Rock shelter almost completed
- It’s gathered at base of mountain to shelter, setting off north
- Border without depth? It offers mountaineer no firm foothold
- Endlessly broadcast rock pieces
- Harsh cry, children having dropped loose rock
- Slippery slope inherent in spurious creed
- The outskirts of Chester in view from loose rocks on hill
Buddy explains!

The straight part
We know that "(loose) rock" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case (loose) rock = scree.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does SCREE mean?
SCREE noun- Loose stony debris on a slope.
- (by extension) Similar debris made up of broken building material such as bricks, concrete, etc.
- A slope made up of loose stony debris at the base of a cliff, mountain, etc.
- To traverse scree downhill.
- A harsh, high-pitched sound or cry (as of a hawk).
- To make a high-pitched cry like that of a hawk.
- To flatten or level concrete while still wet, and remove protruding gravel and stones from the surface.
- A coarse sieve.