Later she’s horribly cruel (9)
I believe the answer is:
heartless
'cruel' is the definition.
(similar in meaning)
'later she's horribly' is the wordplay.
'horribly' is an anagram indicator.
'later'+'shes'='latershes'
'latershes' with letters rearranged gives 'HEARTLESS'.
(Other definitions for heartless that I've seen before include "Cruel and unfeeling" , "Scrooge was" , "hard?" , "with no concern for others?" , "That's very cruel" .)