File doesn’t show a natural building material (10)

I believe the answer is:

fieldstone

I'm a little stuck... Click here to teach me more about this clue!

'material' is the definition.
(fieldstone is a kind of material)

'file doesn't show a natural' is the wordplay.
'file doesn't' anagrams to 'FIELDSTONE'.
But, I am unsure how the anagram is indicated.

'building' acts as a link.

Can you help me to learn more?

I've seen this clue in the Sydney Morning Herald.

Want a hint initially instead of a full solution? Install my app