The most common and most likely answer to this crossword clue is the 9 letter word TWEEDIEST
T
W
E
E
D
I
E
S
T
Buddy explains!
The straight part
We know that "Extremely professorial" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case extremely professorial = tweediest.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does TWEEDIEST mean?
TWEEDIEST adjective- (of clothing) made of tweed, or having a similar rough texture
- (of a person) wearing tweed clothing
- (of a person) preppy