Head of income

1. There was a wide debate on the exact meaning of the profession. Case laws and dictionary meanings were referred for figuring the exact meaning of profession. 
2. A profession should involve specialized skill and intellectual talent in order to be considered a profession. In your case since the content is provided by the client then mere writing cannot be considered a profession. 
3. But if not profession then the next angle would be to look at it as a business. Business involves trade in its widest term and profit on the sale of a product. But we have witnessed certain incomes which are not business and still considered as a business for instance commission income. Income from the commission is considered as a business and not a profession. 
4. From the above analysis if it only involves mere writing where content is already is provided by the client it cannot be considered as a profession. If the content is of own then it will be considered as professional and receipts from the same would qualify as a profession. 
5. It is only based on my own analysis, for any further clarification, it is better to consult an expert. 
Please correct me of the above interpretation has an alternative view.