Protective cover from some treeless heath in Grasmere (9)
I believe the answer is:
sheathing
'protective cover' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'some treeless heath in grasmere' is the wordplay.
'some' indicates a hidden word (some parts of the word are used).
'SHEATHING' is hidden within 'treeless heath in grasmere'.
'from' is the link.
Can you help me to learn more?
(Other definitions for sheathing that I've seen before include "protective covering" , "putting it in a case" .)