linchpin
noun (also lynchpin) uk/ˈlɪntʃ.pɪn/ us/ˈlɪntʃ.pɪn/
the linchpin of 核心，中枢，关键（人物或部分）
the most important member of a group or part of a system, that holds together the other members or parts or makes it possible for them to operate as intended
Woodford is the linchpin of the British athletics team. 伍德福德是英国田径队中的核心人物。