Having let one in, became chatty (6,2)

I believe the answer is:

opened up

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

'chatty' is the definition.
The answer and definition are not the same part of speech. However, adjectives and past participle verbs can occasionally mean the same thing.

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for opened up that I've seen before include "made disclosure" , "started talking" , "started shooting" , "Poured heart out" , "Offered a freer view" .)

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.