The British had one English prime confusion (6)
I believe the answer is:
empire
'the british' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.
'one english prime confusion' is the wordplay.
'one english' becomes 'e' (abbreviation).
'confusion' indicates an anagram.
'prime' is an anagram of 'mpire'.
'e'+'mpire'='EMPIRE'
'had' acts as a link.
Can you help me to learn more?
(Other definitions for empire that I've seen before include "Over which 23 down rules" , "Group of countries under one authority" , "Eg Holy Roman, British or Ottoman" , "In state of New York" , "Jurisdiction" .)