The W-M Learner's Dictionary says:
get above yourself
chiefly Brit : to think you are more important than you really are
- We are pleased by his success, but we worry that he might be getting above himself.
The Cambridge International Dictionary of Phrasal Verbs says:
get above yourself
mainly British
to behave as if you are better than other people
- She's really getting above herself since she got that promotion. [usually in continuous tenses]
The definitions here are a little different, I think. One is "
than you really are" and the other is "
than other people." Which do you think is a better definition?