We see her die twice. She is elsewhere in his timstream to, and as he gets closer to the Trenzalore event, he ‘remembers’ it more. It’s also nothing like River, because each Clara is a separate entity. He’s not meeting the same girl over and over, he’s seeing the same face, name, personality etc, over and over, throughout time and space. He investigates, and can’t find her (girl on the swings short) then, when he is found by her (Missy and the I.T support...) and investigates, he finds...nothing extraordinary. There’s no reason behind events that require a reason. Until there is of course, but it’s not something ‘normal’ even by Doctor standards. First, it’s the actions of another Time Lord, and all of those are time-locked from his perspective, that Time Lord is the Master...who is now a girl. While Moffat establishes that’s a thing, it doesn’t seem to be a thing for the Master (because it isn’t, until a future Doctor who cannot exist without Clara’s intervention, and Missy, make it happen.) and all of this happening by pieces being moved by players from a future that only comes into existence because the pieces were moved. Eleven dies on Trenzalore, Twelve doesn’t exist without Clara (a) fixing his timestream...but she’s only there because he sought her out in the first place because she’s in his timestream and (b) changing the history of the Time War with the Doctors and the Moment...it’s her who reawakens the Doctor in the Warrior (see a again) and (c) gets that message through the crack for the extra cycle (again, see a again for how she’s there) yes, like River, she’s a paradox, but unlike River, she’s a constant bootstrap Paradox, especially through the twisted path involving prophecies and Missy.
She is, very literally, impossible, from every perspective the Doctor has, until she literally makes herself possible...unknowingly. In the olden days we would have called her a Daughter Of Time probably. (Artefacts that loop as bootstrap paradoxes are believed to be made by time herself, to paraphrase something from the New Adventures.
She’s a way more complex event than River or even Bad Wolf, because of how close she is to Doctors existence, and those Time changing events. River, he can figure out most of pretty much right away, and River herself knows outright what she is and who. It’s just information he doesn’t have. No one, including Clara, knows how Clara works, until after Clara herself makes the event happen with no foreknowledge or intent. Missy might know, having a hand in it, but also, can’t know, because without Clara there is no Missy incarnation. Gallifrey itself is part of the predestination...no Clara, no Gallifrey Falls No More, no new regen cycle, no Twelth Doctor and therefore no Missy on the Mondas ship, therefore no Missy, No Clara in the Doctors Time Stream...and loop. With a little squiggle to point out Gallifrey will probably now have the sense to not touch post Raven Clara.
It’s bonkers, because it’s literally impossible.