一心一意

yīxīnyīyì
  1. concentrating one's thoughts and efforts
  2. single-minded
  3. bent on
  4. intently

CEDICT

Entry Composition

1 一心 yīxīn
  1. wholeheartedly
  2. heart and soul
2 一意 yīyì
  1. focus
  2. with complete devotion
  3. stubbornly