final word; voice of authority; authoritative pronouncement
Idiomatic expression referring to a decisive statement from someone in power that settles a matter, often after much discussion. Literally 'a single call of a crane', evoking the commanding voice of a crane that silences other birds.
The meeting dragged on, but the president's final word settled the policy.
We were all discussing it, but in the end it was decided by the department head's authoritative pronouncement.