Center letter: k
Outer letter: l o r a b c
Answers (43):
  rollback
  aback
  alack
  babka
  back
  balk
  ballcock
  barback
  bark
  barrack
  black
  blackball
  block
  bock
  book
  bookrack
  brook
  callback
  clack
  cloak
  clock
  cock
  cook
  cookbook
  cork
  crack
  croak
  crock
  crook
  kabob
  koala
  kola
  kook
  lack
  lark
  lock
  look
  lookbook
  oarlock
  okra
  rack
  rock
  rook