Country reportedly from which pearls come (6)

I believe the answer is:

ostrea

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

'country reportedly from which pearls come' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.

This is all the clue.

Can you help me to learn more?

(Other definitions for ostrea that I've seen before include "What sounds like country" , "country being noisy" , "type of shellfish" .)

I've seen this clue in The Sunday Times and The Times.

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.