Student acquiring knowledge (8)
I believe the answer is:
learning
'knowledge' is the definition.
(learning is a kind of knowledge)
'student acquiring' is the wordplay.
'student' becomes 'l' (as in L-plates for learner drivers).
'acquiring' becomes 'earning' (earning is a kind of acquiring).
'l'+'earning'='LEARNING'
(Other definitions for learning that I've seen before include "Large inn (anag)" , "Lore" , "Cognitive process of acquiring skill or knowledge" , "Erudition - education" , "(Knowledge from) study" .)