If there is an injury ten minutes into a women's college soccer game what is the red shirt rule?

Soccer itself has no "red shirt" rule. The term "red shirt" as applied to college athletics is about eligibility to, in general, play for "another year" because a player "sat out a season" due to injury, scholastic performance or the like. The particulars may require a good bit of interpretation, but they are set down in the case of college athletics by the NCAA. A link to their site is provided.