Take in or suck up (6)
I believe the answer is:
absorb
This clue is a double definition.
'take in' is the first definition.
(synonyms)
'suck up' is the second definition.
(synonyms)
(Other definitions for absorb that I've seen before include "Grip" , "Occupy the mind fully as good book will" , "Draw in, knowledge or food" , "'Imbibe, assimilate (6)'" , "Understand" .)