magic bullet
US /ˈmædʒ.ɪk ˈbʊl.ɪt/
UK /ˈmædʒ.ɪk ˈbʊl.ɪt/

1.
a quick and simple solution to a difficult problem
:
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There's no magic bullet for solving all of society's problems.
•
Many people are looking for a magic bullet to lose weight quickly.