Ranks Scrabble letters required in 'tango'? The opposite (6)

I believe the answer is:

titles

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'ranks' is the definition.

I cannot understand how the remainder of the clue works.

(Other definitions for titles that I've seen before include "Names, of books say" , "Designations or headings" , "Terms" , "Handles" , "'Names of books, plays etc (6)'" .)

I've seen this clue in The Telegraph.

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