Having no gems, perhaps, they guard the earth's treasures (6)

I believe the answer is:

gnomes

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

'earth's treasures' is the definition.
Although both the answer and definition are plural nouns, I don't understand how one could define the other.

'having no gems perhaps they guard' is the wordplay.
'no gems' can be anagrammed to 'GNOMES'.
But, I'm not sure how the anagram is indicated.

'the' is the link.

Can you help me to learn more?

(Other definitions for gnomes that I've seen before include "Legendary creatures" , "Legendary dwarfs" , "Snog me (anag)" , "Influential dwarfs from Zurich?" , "Fairytale dwarfs as garden ornaments" .)

I've seen this clue in the Evening Standard.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.