Most insecure ones media tests unrestrainedly (8)

I believe the answer is:

neediest

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'most insecure' is the definition.
Both the definition and answer are superlative adjectives. Maybe there's a link between them I don't understand?

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

Can you help me to learn more?

(Another definition for neediest that I've seen is " most desperate".)

I've seen this clue in The Telegraph.

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