have something under your belt
idiomPart ofbelt
have something under your belt — idiom
1. to have already gained an experience, qualification, or achievement that you can
1.idiom
Definition
to have already gained an experience, qualification, or achievement that you can rely on later.
Example
With three marathons under her belt, Mira felt ready for the Tokyo race.
Once you have a teaching diploma under your belt, schools will take you seriously.