What a dog does at tree’s exterior? (4)

I believe the answer is:

bark

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

But I can't explain it at all! Could you help me understand?

(Other definitions for bark that I've seen before include "old vessel" , "Tree-skin or dog noise" , "coverage of the Oaks?" , "Dog's cry" , "Cri de cur?" .)

I've seen this clue in The Hindu.

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.