Like Nutmeg in character, one's maliciously cast (9)
I believe the answer is:
'one's maliciously cast' is the definition.
(as in casting aspersions on someone)
'like nutmeg in character' is the wordplay.
'like' becomes 'as'.
'nutmeg' becomes 'I' (where the crossword setter is 'Nutmeg').
'in' indicates putting letters inside.
'character' becomes 'person' (character can mean a person).
'i' placed inside 'person' is 'persion'.
(Other definitions for aspersion that I've seen before include "No praises (anag) - disparaging remark" , "Defamatory suggestion" , "Negative comment" , "Attack on reputation" , "reflection" .)