Taken up as conventional (8)
I believe the answer is:
accepted
This could be a double definition.
'taken up' is the first definition.
'accepted' can be an answer for 'taken' ('accept' can be a synonym of 'take'). I'm not sure about the 'up' bit.
'conventional' is the second definition.
(similar in meaning)
'as' is the link.
Can you help me to learn more?
(Other definitions for accepted that I've seen before include "Taken" , "Took what was offered, being conventional" , "Tolerated; believed to be correct" , "Believed to be valid" , "Conventional -- customary" .)