Clue to warming together (3,2,3)

I believe the answer is:

arm in arm

I'm afraid I can't explain this answer.

(Other definitions for arm in arm that I've seen before include "having intimate contact" , "in friendly fashion" , "Closely linked" , "showing solidarity" , "Linked at the elbows" .)

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.