Center letter: p
Outer letter: a d e h i n
Answers (59):
  headpin
  pinhead
  pinheaded
  aped
  aphid
  apian
  apnea
  append
  appended
  daphne
  dapped
  deadpan
  deadpanned
  deep
  deepen
  deepened
  depend
  depended
  dipped
  epee
  happen
  happened
  heap
  heaped
  hippie
  nape
  napped
  neap
  ninepin
  nipped
  padded
  paean
  paid
  pain
  pained
  panda
  pane
  paned
  panini
  panned
  papa
  peahen
  peed
  peen
  peep
  peeped
  pend
  pended
  penne
  penned
  pepped
  pied
  pine
  pined
  pinned
  pinniped
  pipe
  piped
  pippin