Center letter: a
Outer letter: d f g i n u
Answers (28):
  unfading
  adding
  again
  aging
  aiding
  angina
  dang
  fading
  fang
  fanning
  faun
  fauna
  gadding
  gaff
  gaga
  gagging
  gain
  gaining
  gang
  ganging
  gauging
  iguana
  naan
  nada
  nagging
  naiad
  naif
  nana