Show that you do not just wait for perfect requirements. Describe how you write down your assumptions, validate them quickly, and iterate.
Best answers show proactive clarification: asking targeted questions, writing down assumptions and getting them confirmed, building a minimal prototype to make the discussion concrete, and escalating when ambiguity blocks progress. Strong candidates distinguish between ambiguity they can resolve themselves and ambiguity that needs stakeholder input.
Tests initiative and communication. Developers who freeze when requirements are unclear are a bottleneck. Those who build the wrong thing without asking are expensive. Look for the proactive middle ground.