Castaways' dwellings (4)
I believe the answer is:
huts
'castaways' dwellings' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for huts that I've seen before include "Sheds" , "Cabins" , "Shacks" , "Small crude shelters" , "Wooden shelters" .)