BEIJING—China’s property sector, a major driver of economic growth, has weakened sharply this year as Beijing clamps down on speculators and indebted developers in a broad push to ease financial risks, with prices of new homes down for the first time in six years. In the near term, many analysts expect authorities will try to stabilize the sector, which accounts for a quarter of gross domestic product by some measures, although there is uncertainty over which policy levers Beijing would pull. Authorities would have to address and navigate challenges on multiple fronts: debt risks, cost-of-living pressures, worried homeowners, and the need to boost economic growth. Debt Risks Concerns over growing financial risks are a primary driver of the clampdown. China’s property sector is heavily reliant on credit. As of the end of the second quarter, Chinese developers owed about $5 trillion, or a third of the country’s GDP, according to …