Center letter: r
Outer letter: a b c k l o
Answers (42):
  rollback
  arbor
  arco
  barb
  barback
  barbacoa
  bark
  barrack
  boar
  bookrack
  boor
  brook
  carb
  carob
  carol
  cobra
  collar
  color
  coral
  cork
  corolla
  corral
  crab
  crack
  croak
  croc
  crock
  crook
  labor
  lark
  oarlock
  okra
  oral
  orca
  rack
  roar
  robocall
  rock
  rococo
  roll
  rollbar
  rook