dues-paying
[ dooz-pey-ing, dyooz- ]
/ ˈduzˌpeɪ ɪŋ, ˈdyuz- /
adjective
gaining experience, especially by hard and often unpleasant or uncongenial work: He spent his dues-paying years as a cocktail pianist.
noun
the act or process of gaining experience, especially slowly and laboriously: She had many years of dues-paying before her abilities were recognized.