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

パイプ役[paipuyaku] mediator
悪役[akuyaku] villain
一役[ichiyaku] an office
一役[hitoyaku] role (which someone or something plays in a given situation)
下役[shitayaku] underling

仮役[kariyaku] temporary post
加役[kayaku] temporary extra work
監査役[kansayaku] auditor
顔役[kaoyaku] influential man
区役所[kuyakusho] ward office