Highest sudoku number (4)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
nine
'highest sudoku number' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for nine that I've seen before include "Three squared" , "and 23: Flash in the pan" , "'Possession is... points of the law'" , "A perfect square" , "Number of feline existences" .)