Deep earth left turned over (9)
I believe the answer is:
heartfelt
'deep' is the definition.
(thesaurus)
'earth left turned over' is the wordplay.
'turned over' indicates anagramming the letters.
'earth'+'left'='earthleft'
'earthleft' anagrammed gives 'HEARTFELT'.
(Other definitions for heartfelt that I've seen before include "With sincere passion" , "unfeigned sincerity" , "Most fervent in cardiac way" , "Profound" , "Deeply sincere" .)