Center letter: l
Outer letter: g i k n r u
Answers (42):
  lurking
  giggling
  gill
  gilling
  girl
  glug
  glugging
  gluing
  grill
  grilling
  gull
  gulling
  gurgling
  inkling
  kill
  killing
  kiln
  knurl
  krill
  liking
  linguini
  lining
  link
  linking
  lugging
  luging
  lull
  lulling
  lulu
  lung
  lunging
  lunk
  luring
  lurk
  niggling
  null
  riling
  rill
  ruling
  unliking
  unlink
  unlinking