Can an adjective be separated from its noun by a comma?

That would of course be denied by ministers, adamant the legislation is necessary.

Laura Kuenssberg – BBC News – 15/09/20

In this sentence, I am not quite sure what ‘adamant’ is doing. I very much like the construction but before I launch out and start using it I want to be more clear about what I am doing.

Is there merely an elipsis :

That would of course be denied by ministers (who are) adamant (that) the legislation is necessary.

Or is ‘adamant’ a second subject of the verb ‘is’ (along with ‘legislation’).

It is almost as though ‘adamant’ is performing a verbal function, linking ‘ministers’ to ‘legislation’.

I would be grateful for some sage advice on this, please.