In communication, 'secure language' (4)

I believe the answer is:

thai

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'language' is the definition.
(Thai is an example)

I can't explain the remainder of the clue.

(Other definitions for thai that I've seen before include "Sort of massage" , "From old Siam?" , "Eg, native of Bangkok" , "From Bangkok, for instance" , "eastern language" .)

I've seen this clue in The Independent.

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