Answer:
There is imagery, a simile, and (slight) alliteration.
Step-by-step explanation:
There is imagery in the sentence because the lyrics are so descriptive you can kind of imagine in your head how her face is sinking and wasting away.
The simile is comparing her face to a crumbling pastry. 'her face... crumbling like pastries.'
The slight alliteration comes from the repeating 's' sounds. 'her face seems slowly sinking wasting crumbling like pastries.'
That's all I think... correct me if I'm wrong. :)