Most sagacious (6)
I believe the answer is:
wisest
'most sagacious' is the definition.
('wise' can be similar in meaning to 'sagacious')
This is the entire clue.
(Other definitions for wisest that I've seen before include "Most sage and sagacious" , "Most sensible" , "Closest to Solomon" , "Most astute" , "Most sage and knowledgeable" .)