Northern residents reportedly ruled this place in the East End (8)
I believe the answer is:
reindeer
'northern residents reportedly ruled this place in' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'east end' is the wordplay.
I cannot really understand how this works, but
'east' could be 'e' (abbreviation) and 'e' is found within the answer.
an anagram of 'end' is 'nde' which is within the answer.
This explanation may well be incorrect...
'the' acts as a link.
Can you help me to learn more?
(Other definitions for reindeer that I've seen before include "Arctic ungulate" , "They're called caribou in North America" , "Santa's Prancer, say" , "Rudolph, say" , "Dancer, for one" .)