Dictator back to one Conservative, foolish (7)

I believe the answer is:

idiotic

I'm a little stuck... Click here to teach me more about this clue!

'foolish' is the definition.
(I've seen this before)

'dictator back to one conservative' is the wordplay.
'dictator back' becomes 'idiot' (I can't justify this - if you can you should believe this answer much more).
'to one' becomes 'i' (Roman numeral).
'conservative' becomes 'C' (UK political abbreviation).
'idiot'+'i'+'c'='IDIOTIC'

Can you help me to learn more?

(Other definitions for idiotic that I've seen before include "Senseless" , "Ridiculous" , "Silly" , "Fatuous" , "half-baked" .)

I've seen this clue in The Daily Express.

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