Change the stacking order and move the small part below the rest.
If this is going to be a logo you should expand whatever stroke you applied to it and expand effects (the drop shadow) and create a clean graphic out of it (every shape is outlined by a path). So there's no doubt about how it should look and so that it can be used in all kind of applications
Hye Monika! thanks for your response. By changing the stacking order, do you mean the layers? How can I expand the stroke? If you could go into more detail, it would help out a lot thanks everyone!