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

安全期[anzenki] safe period
暗黒期[ankokuki] eclipse period
一期[ichigo] one's life time
一期[ikki] one term
一期一会[ichigoichie] once-in-a-lifetime encounter (hence should be cherished as such)

一周期[isshuuki] period (in astronomy)
一定期間[itteikikan] fixed interval
延期[enki] postponement
延期になる[enkininaru] to be postponed
沖積期[chuusekiki] alluvial period