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

御中[onaka] stomach
御話中[ohanashichuu] busy (phone)
アル中[aruchuu] alcoholism
π中間子[paichuukanshi] pi meson
暗中[anchuu] in the dark

暗中摸索[anchuumosaku] groping in the dark
意中[ichuu] one's mind
意中の女[ichuunoonna] sweetheart
井の中の蛙大海を知らず[inonakanokawazutaikaiwoshirazu] parochial
一日中[ichinichijuu] all day long

いい年をして[iitoshiwoshite] (in spite of) being old enough to know better
亥年[idoshi] year of the boar
一箇年[ikkanen] one year
一周年[isshuunen] one full year
一年以内に[ichineninaini] within a year

一年間[ichinenkan] (period of) one year
一年生[ichinensei] annual (plant)
一年草[ichinensou] annual (plant)
一年ぢゅう[ichinenjuu] all year round
一両年[ichiryounen] (a) year or two