Under Henry I, archery revised pecking order (9)
I believe the answer is:
hierarchy
'pecking order' is the definition.
(synonyms)
'under henry i archery revised' is the wordplay.
'under' is a charade indicator (letters next to each other).
'henry' becomes 'h' (symbol for the unit of electrical inductance).
'revised' is an anagram indicator.
'archery' with letters rearranged gives 'erarchy'.
'h' put next to 'i' is 'hi'.
'hi'+'erarchy'='HIERARCHY'
(Other definitions for hierarchy that I've seen before include "Top people in an organisation" , "Leaders in church" , "priesthood" , "System with grades of authority ranking one above another" , "priestly government" .)