Crossword Genius

Promising words in this language? (3)

Ross

I believe the answer is:

ido

'this language?' is the definition.
(Ido is an example)

I don't understand how the remainder of the clue works.

(Other definitions for ido that I've seen before include "Obscure language" , "International language" , "Say yes in marriage" , "Marriage response" , "Prepared tongue" .)

I've seen this clue in The Times.
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