High grade knowledge crammed in can be absorbed (5,2)
I believe the answer is:
taken in
'absorbed' is the definition.
('take in' can be a synonym of 'absorb')
'high grade knowledge crammed in can' is the wordplay.
'high grade' becomes 'a' (I can't explain this - if you can you should give a lot more credence to this answer).
'knowledge' becomes 'ken' (ken is a kind of knowledge).
'crammed in' is an insertion indicator.
'can' becomes 'tin' ('tin' can be a synonym of 'can').
'a'+'ken'='aken'
'aken' put within 'tin' is 'TAKEN IN'.
'be' is the link.
(Other definitions for taken in that I've seen before include "hoodwinked" , "Allowed access" , "Conned" , "Admitted - received - deceived" , "Deceived; accepted" .)