Acquires knowledge (6)
I believe the answer is:
learns
'acquires knowledge' is the definition.
('learn' can be a synonym of 'acquire knowledge')
This is all the clue.
(Other definitions for learns that I've seen before include "Gains understanding from study or experience" , "Finds out" , "Imbibes knowledge" , "Teaches non-standard" , "Acquires knowledge or skills" .)