Distinguished senior professor solver once punched (5)

I believe the answer is:

doyen

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

'distinguished senior' is the definition.
'doyen' can be an answer for 'senior' (I've seen this in another clue). I am unsure of the 'distinguished' bit.

I can't explain the remainder of the clue.

Can you help me to learn more?

(Other definitions for doyen that I've seen before include "Senior male member of a group" , "Prominent group member" , "Senior practitioner" , "Senior member of a professional group" , "Senior person" .)

I've seen this clue in the Sydney Morning Herald.

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