Star losing the head is supported and isn't punished (12)

I believe the answer is:

unsanctioned

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'star losing the head is supported' is the definition.
I can't judge whether this definition defines the answer.

'isn't punished' is the wordplay.
'isn't' becomes 'un' (I can't justify this - if you can you should believe this answer much more).
'punished' becomes 'sanctioned' (I've seen this before).
'un'+'sanctioned'='UNSANCTIONED'

'and' acts as a link.

Can you help me to learn more?

(Another definition for unsanctioned that I've seen is " Not approved".)

I've seen this clue in The Irish Times.

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