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

一瞬[isshun] moment
一瞬間[isshunkan] moment
瞬く[matataku] to twinkle (e.g. stars)
瞬間[shunkan] moment
瞬間電断[shunkandendan] power flicker

瞬刻[shunkoku] moment
瞬時[shunji] moment
瞬断[shundan] power flicker
瞬き[mabataki] blink (of eyes)
瞬く間に[matatakumani] in the twinkling of an eye