Profoundly knowledgeable (7)
I believe the answer is:
erudite
'profoundly knowledgeable' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for erudite that I've seen before include "Learned and scholarly" , "Having deep knowledge" , "Having or showing great knowledge or learning" , "Rue diet for the learned" , "Well educated, having great learning" .)