In central Sweden tribal rulers can be taken in (6)
I believe the answer is:
edible
'can be taken in' is the definition.
(that which can be eaten or taken into the body)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for edible that I've seen before include "(Of food) harmless" , "Eatable" , "It's all right to scoff" , "I can swallow that!" , "suited to diners" .)