I'm an acting teacher, and I worked this summer with a trans-sexual actor, someone who has had facial surgery, hormones, but not the big "chop" yet. Her gender was female, her sex was male, though this was generally perceived as being off-limits in discussions. Other teachers on the course struggled with calling this person "she", mostly because they still connected with some very masculine aspects of her voice and body, though her mannerisms, clothing and name were extremely feminine. In this case, the term gender was very helpful.