I want to ask a question about small-scale enterprises. What is the best site that can be asked on?
Here are some options for you, it will largely depend on what your question is actually about:
Without knowing the exact content of your question I would say that On Startups is your best bet - see if there is a precedent for the question you want to ask or look on the per-site meta.
OnStartups would have perhaps suited you well, however has now been closed due to lack of activity.
How small? What kind of "business" questions?
If you mean "very small", OnStartups may fit the bill.
If the questions is about general professional advice for work, the workplace site might fit.