Not given a thought except by the United Nations? (12)

'united nations?' is the definition.
The answer and definition are not the same part of speech. However, past participle verbs and adjectives can occasionally define each other.

'not given a thought except' is the wordplay.
I cannot quite see how this works, but
'not' could be 'con' (I've seen this in other clues) and 'con' is found within the answer.
'thought' could be 'side' (side is a kind of thought) and 'side' is present in the answer.
The remaining letters 'unred' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).

'by the' is the link.

Can you help me to learn more?