Act as an SEO strategist with 5+ years of experience in content clustering and pillar-based strategies. Guide me step-by-step on how to create a high-performing content cluster strategy for [INDUSTRY/NICHE], targeting [PRIMARY KEYWORD] as the pillar topic. Include the following details: 1. How to identify and prioritize [SUBTOPIC KEYWORDS] semantically related to the pillar. 2. Best practices for interlinking between cluster content and the pillar page. 3. How to measure success using [METRICS LIKE TRAFFIC, RANKINGS, OR CONVERSIONS]. Provide actionable insights, tools (e.g., Ahrefs, SEMrush), and a template for organizing the cluster. Keep the tone professional yet accessible for marketers.