Old Henry, a soldier, forced back Amerindian (7)
I believe the answer is:
arapaho
'amerindian' is the definition.
(Native American tribe)
'old henry a soldier forced back' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'henry' becomes 'h' (symbol for the unit of electrical inductance).
'soldier' becomes 'para' (para is a kind of soldier).
'forced back' shows that the letters should be reversed in order.
'o'+'h'+'a'+'para'='ohapara'
'ohapara' back-to-front is 'ARAPAHO'.
(Other definitions for arapaho that I've seen before include "Brave" , "North American native" , "tribesman" , "tribe member" , "Indians" .)