Redesigned MG is meant to show pulling power (9)
I believe the answer is:
magnetism
'pulling power' is the definition.
(thesaurus)
'redesigned mg is meant' is the wordplay.
'redesigned' indicates an anagram.
'mg'+'is'+'meant'='mgismeant'
'mgismeant' with letters rearranged gives 'MAGNETISM'.
'to show' acts as a link.
(Other definitions for magnetism that I've seen before include "Charisma" , "Drawing power" , "Attraction" , "Attractive force" .)