One moving into residence after aristocrat kept up great friendliness (8)
I believe the answer is:
bonhomie
'great friendliness' is the definition.
(bonhomie is friendliness)
'one moving into residence after aristocrat' is the wordplay.
'one' becomes 'I' (Roman numeral).
'moving into' is an insertion indicator.
'residence' becomes 'home' (home is a kind of residence).
'after' is a charade indicator (letters next to each other).
'aristocrat' becomes 'bon' (I can't justify this - if you can you should believe this answer much more).
'i' put into 'home' is 'homie'.
'homie' put after 'bon' is 'BONHOMIE'.
'kept up' is the link.
This may not be right. Some or all of it may belong to another bit of the clue.
(Other definitions for bonhomie that I've seen before include "Warmth" , "convivial feeling" , "Good fellowship or genial manner in France" , "Inventory" , "Genial manner from hobo in me" .)