Isolate and get grease off (9)
I believe the answer is:
segregate
'isolate' is the definition.
(thesaurus)
'get grease off' is the wordplay.
'off' is an anagram indicator.
'get'+'grease'='getgrease'
'getgrease' anagrammed gives 'SEGREGATE'.
'and' acts as a link.
(Other definitions for segregate that I've seen before include "Put apart from others for easter egg" , "Keep away from" , "Isolate, separate" , "Keep apart" , "Separate by race or religion" .)