肝心な

crucial

→ 肝心だ
phrase Uncommon #17,807
crucial Used for something essential or especially important. The な form comes before nouns, while 肝心だ is used at the end of a sentence.
JA: 健康には、十分な睡眠が肝心な要素です。
EN: Adequate sleep is a crucial factor for good health.

心臓発作の後数分肝心なんです

The few minutes after a heart attack are critical.

肝心な所で失敗した

I failed when it mattered most.

肝心なのは何を読むではなくてどう読む

The important thing isn’t what you read, but how you read it.

なんでこの肝心な時にトムがいないんだよ

Why isn't Tom here when we need him most?} } 👎? Need valid JSON only. The format says object; don't add. Ensure exclamation perhaps. Translation natural:

そこが肝心なところだった

That was the crucial point.

— コーラス (2004)

肝心なところで手を抜かない

Don’t cut corners where it matters most.