Renovated seediest part of the North (8)
I believe the answer is:
teesside
'part of the north' is the definition.
(area of the north of England)
'renovated seediest' is the wordplay.
'renovated' is an anagram indicator.
'seediest' with letters rearranged gives 'TEESSIDE'.
(Other definitions for teesside that I've seen before include "NE urban area" , "Area round Middlesbrough" , "Area in NE England" , "NE conurbation" , "NE industrial zone" .)