老鼠拖木锨，大头在后头
lǎo​shǔ​tuō​mù​xiān, dà​tóu​zài​hòu​tou

tip of iceberg

老鼠拖木锨，大头在后头 (老鼠拖木鍁，大頭在後頭) lǎo​shǔ​tuō​mù​xiān, dà​tóu​zài​hòu​tou
tip of iceberg
indicates that the most significant, difficult, or substantial part of a situation is yet to follow; the worst is yet to come

Sources
Definitions
CC-CEDICT