Take in compendium (6)
I believe the answer is:
digest
I believe this clue is a double definition.
'take in' is the first definition.
(I've seen this in another clue)
'compendium' is the second definition.
(I know that digest is a type of compendium)
(Other definitions for digest that I've seen before include "Absorb, food or information" , "Break down in the stomach" , "Take in (information or food)" , "Make more concise" , "Gradually come to understand" .)