Center letter: t
Outer letter: a c d h k r
Answers (34):
  hardtack
  arhat
  attach
  attack
  attar
  attract
  carat
  cart
  cataract
  catarrh
  catch
  chart
  chat
  dart
  data
  drat
  hardhat
  hart
  hatch
  hath
  hatha
  hatrack
  karat
  kart
  ratatat
  tach
  tack
  tact
  tart
  tartar
  that
  thatch
  track
  tract