Starting a clothing brand in Europe and ensuring ethical sourcing practices is crucial to maintain a responsible and sustainable business. Here are some steps you can take to ensure your suppliers do not use child labor or exploit workers:

1. Research and Select Suppliers: Start by researching potential suppliers who prioritize ethical practices. Look for certifications such as Fair Trade, Global Organic Textile Standard (GOTS), or Worldwide Responsible Accredited Production (WRAP). These certifications ensure compliance with fair labor practices and sustainability standards.

2. Visit Suppliers in Person: If possible, visit the supplier's facilities personally to assess their working conditions, employee treatment, and age verification processes. Observe the factory environment, talk to workers, and assess overall compliance with labor laws.

3. Request Supplier Audits: Ask suppliers to provide third-party audits or certifications to validate their ethical practices. Independent auditing organizations like Sedex, Social Accountability International (SAI), or Fair Wear Foundation conduct assessments to ensure compliance with labor standards.

4. Implement Supplier Code of Conduct: Develop a comprehensive code of conduct that outlines your expectations regarding labor practices, including a prohibition on child labor and ensuring fair wages. Share this code with potential suppliers and require their commitment to adhere to it.

5. Engage in Transparent Communication: Establish open lines of communication with suppliers to foster a transparent relationship. Regularly discuss labor practices, compliance, and any concerns that arise. Encourage suppliers to share information about their supply chain and subcontractors.

6. Conduct Supply Chain Mapping: Trace your supply chain to identify all tiers of suppliers. This helps ensure transparency and accountability throughout the production process. Use tools like Sourcemap or Open Apparel Registry to map your supply chain and identify potential risks.

7. Collaborate with Ethical Organizations: Partner with organizations that promote ethical practices in the fashion industry. For example, the Ethical Trading Initiative (ETI) or Fair Trade International can provide guidance, resources, and support for responsible sourcing.

8. Stay Informed: Keep up-to-date with industry news, regulations, and reports on labor practices. Organizations like the Clean Clothes Campaign, Fashion Revolution, or the Fair Labor Association publish reports on the fashion industry, highlighting brands' ethical performance and transparency.

Remember, ethical sourcing is an ongoing commitment, and maintaining strong relationships with suppliers is crucial. Regular audits, transparent communication, and collaboration with ethical organizations will help ensure your clothing brand operates responsibly and supports fair labor practices.

Note: While I have provided general guidance, it is essential to consult legal and industry experts for specific advice tailored to your business.