The Time of the Doctor - S7-E17
Other mistake: While looking around the Doctor's room, one of the children's drawings Clara passes by has the TARDIS in it... when the TARDIS has been absent for all of the 300 years the Doctor has spent on Trenzalore up to this point, so none of the pictures existing now should have the time machine present. And it's not a particularly weathered picture, either, suggesting it can't be from the beginning of his stay on the planet. (00:31:47)
Chosen answer: No, no information is avalible for the identity of the entity.
Repo_Man