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

一円[ichien] one yen
一円玉[ichiendama] one-yen coin
一円札[ichiensatsu] one-yen bill
円か[madoka] round
円やか[maroyaka] round

円グラフ[engurafu] pie graph
円安[enyasu] cheap yen
円為替[engawase] yen exchange
円域[eniki] yen bloc