Does he stoop to all kinds of villainy? (4,8)

I believe the answer is:

arch criminal

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

'stoop to all kinds of villainy?' is the definition.
I can't tell whether this definition defines the answer.

'does he' is the wordplay.
I cannot really understand how this works, but
'he' could be 'arch' and 'arch' is located in the answer.
The remaining letters 'criminal' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?

I've seen this clue in the Evening Standard.

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