ちょっと一杯[chottoippai] let's have a quick drink
ばつ一[batsuichi] being once divorced
一向[hitaburu] nothing but
サラダ一皿[saradahitosara] plate of salad

安全第一[anzendaiichi] safety first
一か八か[ichikabachika] sink or swim
一っ走り[hitoppashiri] spin (as in 'take a car for a spin')
一つ一つ[hitotsuhitotsu] one-by-one

せざるを得ない[sezaruwoenai] cannot avoid doing
一挙両得[ikkyoryoutoku] killing two birds with one stone
一得[ittoku] one advantage
一得一失[ittokuisshitsu] gaining some and losing some
課税所得[kazeishotoku] taxable income

我が意を得る[wagaiwoeru] to approve of
会得[etoku] understanding
獲得[kakutoku] acquisition
既得[kitoku] vested
既得権[kitokuken] vested rights