Tongue rook kept inside beak (5)

I believe the answer is:

norse

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

'tongue' is the definition.
(Norse is an example)

I cannot understand how the remainder of the clue works.

(Other definitions for norse that I've seen before include "Ancient Scandinavian language" , "Snore (anag)" , "Viking" , "Of old Scandinavia" , "Old Scandinavian language" .)

I've seen this clue in The Sunday Times and The 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.