Haunted out of Chateaubriand, or that's what they're saying in Tunis (6)

I believe the answer is:

arabic

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'saying in tunis' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Maybe they are linked in a way I don't understand?

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for arabic that I've seen before include "Language (of numbers)" , "Official language of Egypt" , "connected with gum" , "Final" , "Semitic language" .)

I've seen this clue in The Irish Times.

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