Yes, you can absolutely be an entrepreneur and an engineer. Anyone can be entrepreneur if they only want it enough. On a more specific note, being an entrepreneur is a mindset, it doesn't require a degree of any sort. Being an entrepreneur is very much like being an artist in the business world.
You need to be creative, business focused and oriented, sharp, determined and many more qualities (in order to be a successful entrepreneur at least). None of these qualities though collide with being an engineer. You would probably have many qualities and advantages just by the fact you are an engineer. If the business you are trying to establish has something to do with your field of engineering then that it is an amazing advantage.
Engineers use a different set of vocabulary and references that make it difficult to communicate with the average person. As an entrepreneur, you're going to need to communicate your product and service offerings at a level that the customer will understand. So working on simplifying your sentences and vocabulary can help.
So I would say yes, you can definitely be an engineer and an entrepreneur.