Possible Clues:

• It would seem that he was 6 across inversely
• US poet of high standing
• American poet, author of 17
• This chap may stand head and shoulders above others of his poetic peers
• Henry Wadsworth --, US poet
• Poet of many words, mate!
• Poet slipped in extended cry of pain
• Song of_Hiawatha poet
• Was he any sort of great poet at all?
• Was he high enough for Hiawatha? (10)