Drink in, assimilate (6)
I believe the answer is:
imbibe
I believe this clue is a double definition.
'drink in' is the first definition.
(I've seen this before)
'assimilate' is the second definition.
(I know that assimilate can be written as imbibe)
(Other definitions for imbibe that I've seen before include "Drink in - assimilate" , "Tope" , "Drink or absorb into mind" , "Quaff" , "Drink, take in" .)