She joined the team as a walk-on and eventually became a starter through hard work.

walk-on 是由动词短语 walk on（字面意思是"走上去"）组成的复合名词，在体育领域特指"非正式队员"或"未经招募的队员"，通常指没有获得体育奖学金而加入校队的运动员。