One slum I refurbish - with this paint? (8)
I believe the answer is:
emulsion
'this paint?' is the definition.
(I've seen this before)
'one slum i refurbish' is the wordplay.
'refurbish' indicates anagramming the letters (I've seen 'refurbished' mean this).
'one'+'slum'+'i'='oneslumi'
'oneslumi' is an anagram of 'EMULSION'.
'with' is the link.
(Other definitions for emulsion that I've seen before include "Type of paint" , "Wall paint" , "Mixture involving two liquids which do not readily combine" , "Mixture of insoluble liquids" .)