Pert beast disturbed soil (9)
I believe the answer is:
bespatter
'soil' is the definition.
(thesaurus)
'pert beast disturbed' is the wordplay.
'disturbed' indicates anagramming the letters (the order of letters is disturbed).
'pert'+'beast'='pertbeast'
'pertbeast' anagrammed gives 'BESPATTER'.
(Other definitions for bespatter that I've seen before include "Spray with droplets" , "Make mess of" , "Defame" , "Dirty" .)