決め手
Common
Noun
1
noun (common) (futsuumeishi)
decider;person who decides
2
noun (common) (futsuumeishi)
decisive factor;clincher;key;trump card;winning move;decisive blow;conclusive evidence
ワインが食事の決め手です。
Wine can make the meal.
Other forms
極め手 【きめて】 (rarely used kanji form)