American article on holm oak revised (9)
I believe the answer is:
oklahoman
'american' is the definition.
(I've seen this before)
'article on holm oak revised' is the wordplay.
'article' becomes 'an' (English indefinite article).
'on' means one lot of letters go next to another.
'revised' indicates an anagram.
'holm'+'oak'='holmoak'
'holmoak' with letters rearranged gives 'oklahom'.
'an' after 'oklahom' is 'OKLAHOMAN'.
(Other definitions for oklahoman that I've seen before include "American" , "US resident" , "from Tulsa?" .)