Claire Bloom's role is very vague right now; simply describing herself as playing a seer-like or protecting role for the Doctor. Since the Doctor, in at least some of the novels, has been referred to as Time's Champion and this is the End of Time, wouldn't it be a wonderfully ridiculous twist if she is playing the anthropomorphic personification of Time? If you want more silly 'evidence' (yes, I'm being very lighthearted about this one) then this could have been mildly foreshadowed by the Trickster's description of holding the Key to Time, although that could really refer to any mention of time (with or without that significant 'T'). Still, if she were to portray Time, then I'd hope that the sound of ringing glass would follow her as other portrayals have described.