earn (one's) corn
To be worthy of the money that one is being paid. I think you should hire the most experienced candidate because she'll definitely earn her corn.
earn your corn
BRITISHIf someone earns their corn, they are successful and therefore justify the money that has been spent, for example on employing or training them. New striker, Steve Menzies, earned his corn with a last-minute goal. Managers earn their corn in these difficult circumstances.
earn your corn
put in a lot of effort for your wages. British informal