clumsy as a bull in a china shop

Translations
неловкий как слон в посудной лавке
When it comes to delicate matters, he's clumsy as a bull in a china shop.
Когда дело доходит до деликатных вопросов, он неловкий как слон в посудной лавке.
Definitions
Extremely awkward or careless in a situation where careful handling is required, often causing disruption or damage due to lack of delicacy.