Center letter: a
Outer letter: d i l n v y
Answers (52):
  invalidly
  allay
  ally
  anal
  anally
  annal
  anvil
  avail
  avian
  avid
  avidly
  daddy
  daily
  dally
  dandily
  dandy
  daylily
  dial
  dillydally
  diva
  divan
  dyad
  inlaid
  inland
  inlay
  invalid
  lady
  laid
  lain
  lanai
  land
  landlady
  lava
  naan
  nada
  naiad
  nail
  nana
  nanny
  naval
  navy
  vain
  vainly
  valid
  validly
  vandal
  vanilla
  vanillin
  vial
  villa
  villain
  villainy