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

一脈[ichimyaku] (a) vein
冠動脈[kandoumyaku] coronary artery
金脈[kinmyaku] (questionable) financial connections
頸静脈[keijoumyaku] jugular vein
けい動脈[keidoumyaku] carotid artery

鉱脈[koumyaku] vein (of ore)
山脈[sanmyaku] mountain range
支脈[shimyaku] spur
主脈[shumyaku] main mountain range
人脈[jinmyaku] personal connections