一槌定音

variant of 一錘定音|一锤定音[yi1 chui2 ding4 yin1]

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

mallet / pestle / beetle (for wedging or ramming)

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

to call the tune / to make the final decision

sound / noise / note (of musical scale) / tone / news / syllable / reading (phonetic value of a character)