Is not Dr Tooth possibly an alias for one? (12)

I believe the answer is:

orthodontist

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

'an alias for one?' is the definition.
I can't judge whether this definition defines the answer.

'is not dr tooth possibly' is the wordplay.
'possibly' indicates anagramming the letters.
'is'+'not'+'dr'+'tooth'='isnotdrtooth'
'isnotdrtooth' is an anagram of 'ORTHODONTIST'.

Can you help me to learn more?

(Other definitions for orthodontist that I've seen before include "One who straightens up teeth" , "Special dentist" .)

I've seen this clue in The Guardian.

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