> - ‘gender’ is being misused as a synonym ‘gender roles’, which are defined by one’s sex.

Sure, “Gender” = “What gender role(s?) a person plays” is one way to put the social definition of gender. (Seems pretty succinct and workable, so you can drop the “misused”.)

Here's where you go wrong, though: Gender, in terms of what gender roles people play, is not always determined purely by biological sex.

There, no need to be confused any more. HTH!