earn (your) stripes

to do something to show that you deserve a particular rank or position and have the skills needed for it.

She earned her stripes as a junior reporter before becoming education correspondent.

• be the armpit of the universe
• be the armpit of the world
• be the bee's knees
• be the best of a bad bunch
• be the best of a bad lot
• be the brains behind
• be the brains behind something
• be the cat's whiskers
• be the dead spit of
• be the dead spit of someone
• be the end of the line
• be the end of the road
• be the end of the world
• be the exception that proves the rule
• be the full quid
• be the last word in
• be the last word in something
• be the life and soul of the party
• be the light of life
• be the light of someone's life
• be the living end
• be the making of
• be the making of someone
• be the marrying kind
• be the meat in the sandwich