Middle or old Persian tongue (6)

I believe the answer is:

median

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'middle' is the definition.
(I've seen this in another clue)

I don't understand the rest of the clue.

(Other definitions for median that I've seen before include "The middle of a series of values" , "Situated or passing through the middle" , "statistical quantity" , "Relating to the middle value" , "NI made it into the middle" .)

I've seen this clue in the Sydney Morning Herald.

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