Education expert, most senior, flexible (10)

I believe the answer is:

montessori

'education expert' is the definition.
(educational theorist Maria Montessori)

'most senior flexible' is the wordplay.
'flexible' indicates an anagram (the word is bent into a new form).
'most'+'senior'='mostsenior'
'mostsenior' with letters rearranged gives 'MONTESSORI'.

(Another definition for montessori that I've seen is " education expert".)

I've seen this clue in The Times.

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