vexed question

Given what happened, that would be a vexed question.

On the vexed question of exactly how drum 'n' bass and jungle differ, my final answer is: I don't know.

How business leaders should engage with politics is a vexed question, especially in these febrile times.

Those recommendations would cover "identifying and expanding sources of funding" - referring to the vexed question of which countries should pay into the new fund.

There is also the vexed question of what kind of security guarantees should be offered to encourage private investment in the rebuilding.