Fine-grained soil (5)
I believe the answer is:
loess
'fine-grained soil' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for loess that I've seen before include "that may be deposited" , "desposit" , "Compacted wind-blown sediment (geology)" , "Wind-deposited silt" , "geological feature" .)