Center letter: r
Outer letter: a c g i n u
Answers (71):
  accruing
  uncaring
  agar
  agrarian
  airing
  arancini
  arcana
  arcing
  arguing
  aria
  arnica
  arraign
  arraigning
  arranging
  augur
  auguring
  aura
  cairn
  caring
  cigar
  circa
  cirri
  crag
  crania
  craning
  cringing
  curing
  garaging
  gracing
  grain
  graining
  gran
  grin
  grinning
  guar
  guru
  incur
  incurring
  ingrain
  ingraining
  inuring
  inurn
  inurning
  narc
  nigiri
  racing
  raga
  ragging
  raging
  ragu
  rain
  raining
  rang
  ranging
  rani
  raring
  ricin
  ricing
  rigging
  ring
  ringing
  ruin
  ruing
  ruining
  rung
  runic
  running
  unrig
  unrigging
  urging
  uric