Written translation on film — it’s missing. Not immediately obvious (6)

I believe the answer is:

subtle

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'not immediately obvious' is the definition.
(subtleties are not immediately obvious)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for subtle that I've seen before include "Very nice" , "Difficult to analyse; understated" , "Highly refined" , "Indirect, difficult to detect" , "Delicate - crafty - indirect" .)

I've seen this clue in The Times.

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