Go get soil sorted by an earth scientist (9)
I believe the answer is:
geologist
'an earth scientist' is the definition.
(I know that geologist is a type of earth scientist)
'go get soil sorted' is the wordplay.
'sorted' is an anagram indicator.
'go'+'get'+'soil'='gogetsoil'
'gogetsoil' is an anagram of 'GEOLOGIST'.
'by' is the link.
(Other definitions for geologist that I've seen before include "One studying the earth's structure" , "One studying rocks" , "Specialist in the earth's history recorded in rocks" , "One studying the earth's crust" , "Specialist in the history of the earth in rocks" .)