Adopted new pose on American edition (8)
I believe the answer is:
espoused
'adopted' is the definition.
('espouse' can be a synonym of 'adopt')
'new pose on american edition' is the wordplay.
'new' is an anagram indicator.
'on' says to put letters next to each other.
'american' becomes 'us'.
'edition' becomes 'ed'.
'pose' with letters rearranged gives 'espo'.
'espo'+'us'+'ed'='ESPOUSED'
(Other definitions for espoused that I've seen before include "Advocated" , "Gave one's support to" , "embraced" , "Adopted, as of a cause" , "Championed or took up cause" .)