一言為定

(idiom) it's a deal / that's settled then

one / single / a (article) / as soon as / entire; whole; all; throughout / "one" radical in Chinese characters (Kangxi radical 1) / also pr. [yao1] for greater clarity when spelling out numbers digit by digit

one sentence / brief remark

words / speech / to say / to talk

as (in the capacity of) / to take sth as / to act as / to serve as / to behave as / to become / to be / to do / by (in the passive voice)

because of / for / to

to set / to fix / to determine / to decide / to order