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

威張り散らす[ibarichirasu] to domineer
胃散[isan] stomach medicine
逸散に[issanni] at top speed
一目散[ichimokusan] at full speed
一目散に[ichimokusanni] at full speed

雲散霧消[unsanmushou] vanishing like mist
解散[kaisan] breakup
拡散[kakusan] scattering
閑散[kansan] deserted (esp. store, market, town, streets)
言散らす[iichirasu] to spread (a report)