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

一軍[ichigun] an army
１等軍曹[ittougunsou] sergeant first-class
一泊行軍[ippakukougun] an overnight march
援軍[engun] reinforcement
海軍[kaigun] navy

凱旋軍[gaisengun] returning victorious army
救世軍[kyuuseigun] Salvation Army
共産軍[kyousangun] communist army
郷軍[gougun] veteran
空軍[kuugun] Air Force