Crossword Genius

Firm in Arctic needs no introduction (5)

Ross

I believe the answer is:

rigid

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

'firm' is the definition.
(thesaurus)

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for rigid that I've seen before include "Hard" , "Frozen" , "strict" , "Firmly fixed" , "stern" .)

I've seen this clue in the Irish Times (Crosaire) and the Irish 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.