Hi J. - This may sound strange to you, and please read with an open heart - because that is what it is sent with.
But.... why does she need to play dress-up? I think if you think about it, maybe this is more about you than her.
Something to consider might be to just let her be who she wants to be - accept her as she is and find other entertainment for her. At 3, you have a very long road ahead of you as far as your child growing into who she is - the sooner you can change your perspective towards supporting her in that, the better for both of you!
And what I mean by this is simply that we all have our own needs, wants and desires. It seems strange and odd that our children aren't always what we expect or think they should be, and our immediate reaction is to "normalize" them towards what we see we want for them. Does this make sense? It is natural. (Not necessarily right, but natural nonetheless.)
But maybe you restrict her TV watching (a wonderful thing!) so maybe she doesn't see all the fantasy that's out there. Or maybe she's going to be an Dr. or Engineer and her brain just works different... Maybe her imagination isn't her top priority.
If she were kicking the cat, or hurting animals, I would be concerned. If she were putting herself in danger, then I would be concerned. These are lessons of love and compassion, and safety.
But if we want our children to be accepting of our differences as people, then we have to start by showing them the same example. That is a lesson in who we choose to be in the world and how we teach our children through that.
All that to say - relax! Have fun! Three is my favorite age... Go do other fun stuff - and thank GOD you don't have a HUGE plastic bin in her room full of old clothes that don't fit anymore.
She's fine. She's just her. Unique is wonderful!