Due to reformation, American's obedient (7)
I believe the answer is:
duteous
'obedient' is the definition.
('duteous' can be similar in meaning to 'obedient')
'due to reformation american's' is the wordplay.
'reformation' indicates anagramming the letters.
'american' becomes 'us'.
'due'+'to'='dueto'
'dueto' is an anagram of 'duteo'.
'duteo'+'us'='DUTEOUS'
(Other definitions for duteous that I've seen before include "Dutiful (archaic)" , "Devoted" , "Obedient" , "Attentive to obligations" , "Conscientious" .)