Stemming a terrible charm (9)
I believe the answer is:
magnetism
'charm' is the definition.
(thesaurus)
'stemming a terrible' is the wordplay.
'terrible' is an anagram indicator.
'stemming'+'a'='stemminga'
'stemminga' anagrammed gives 'MAGNETISM'.
(Other definitions for magnetism that I've seen before include "Attractive force" , "Drawing power" , "Charisma" , "Attraction" .)