What, historically, Martha became, following double first (4)

I believe the answer is:

lady

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

'double first' is the definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps you can see a link between them that I don't see?

I can't explain the rest of the clue.

Can you help me to learn more?

(Other definitions for lady that I've seen before include "Lord's partner" , "Title for a knight's wife" , "Woman, maybe titled" , "Female peer" , "Female title" .)

I've seen this clue in The Guardian.

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.