Respond to TV idea unexpectedly started again (11)

I believe the answer is:

reactivated

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'started again' is the definition.
The definition and answer can be both related to change as well as being past participle verbs.
Maybe they are linked in a way I don't understand?

'respond to tv idea unexpectedly' is the wordplay.
'respond to' becomes 're-act' (I've seen this in another clue).
'unexpectedly' is an anagram indicator.
'tv'+'idea'='tvidea'
'tvidea' anagrammed gives 'ivated'.
'react'+'ivated'='REACTIVATED'

Can you help me to learn more?

I've seen this clue in The Daily Express.

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