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

一週[isshuu] one week
一週間[isshuukan] one week
今週[konshuu] this week
今週中に[konshuujuuni] before the week is out
さ来週[saraishuu] week after next

七週の祭[nanamawarinoiwai] the Feast of Weeks
七週の祭り[nanashuunomatsuri] the Feast of Weeks
週刊[shuukan] published weekly
週刊雑誌[shuukanzasshi] weekly magazine