There has been a lot of talk from the Doctor this series about his 'duty of care' towards Clara and her seemingly reckless enthusiasm for jumping into the next adventure is certainly worrisome. That theme raised its head quite prominently in The Girl Who Died when the Doctor discussed the grief he would feel when she eventually passed. Since its return in 2005 Doctor Who has never actually gone through with killing a companion - in fact we haven't seen this happen to a main character since Adric in 1982's Earthshock. It is a question we asked after The Witch's Familiar and it is something that is becoming more apparent as the series progresses. There are so many hints that Clara will meet a grisly end, it will be surprising if she makes it to the end credits of series finale Hellbent alive. In The Woman Who Died Clara confidently stated that she "wasn't going anywhere." If that isn't a surefire sign that her time is almost up, I don't know what is.