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

暗部[anbu] dark side (of nature, town, etc.)
鞍部[anbu] col
医学部[igakubu] medical faculty
一局部[ichikyokubu] one part
一部[ichibu] one part

一部始終[ichibushijuu] full particulars
一部分[ichibubun] part
陰部[inbu] the genital area
営業部[eigyoubu] sales department
掩護部隊[engobutai] covering force