After Henry I, archery reshaped the pecking order (9)
I believe the answer is:
hierarchy
'pecking order' is the definition.
(synonyms)
'after henry i archery reshaped' is the wordplay.
'after' means one lot of letters go next to another.
'henry' becomes 'H' (symbol for the unit of electrical inductance).
'reshaped' indicates an anagram.
'archery' anagrammed gives 'erarchy'.
'h'+'i' is 'hi'.
'hi'+'erarchy'='HIERARCHY'
'the' acts as a link.
(Other definitions for hierarchy that I've seen before include "System arranged in successive grades" , "System of status rankings" , "priesthood" , "Pecking order" , "Governing levels of organisation" .)