Sets apart site also disintegrating (8)
I believe the answer is:
isolates
'sets apart' is the definition.
('isolate' can be a synonym of 'set apart')
'site also disintegrating' is the wordplay.
'disintegrating' indicates anagramming the letters (I've seen 'disintegrated' mean this).
'site'+'also'='sitealso'
'sitealso' with letters rearranged gives 'ISOLATES'.
(Other definitions for isolates that I've seen before include "Sets apart from others" , "Oils seat (anag.)" , "Places apart or alone" , "Keeps apart from others" .)