Answer:

TWAS

AnswerCrossword Clue
TWAS"A Visit from St. Nicholas" opener
TWAS".. the night before ..."
TWASClement C. Moore opener
TWASHoliday verse starter
TWAS"... the Night..."
TWASChristmas poem beginning
TWASMoore opening
TWASHoliday poem starter
TWAS"Jabberwocky" start
TWASStart of "Jabberwocky"
TWAS" .. brillig ... "
TWAS"Jabberwocky" opener
TWAS".. the night before..."
TWAS"Jabberwocky" starter
TWASFirst word in "Jabberwocky"
TWAS".. brillig..."
TWAS"... brillig, and the slithy toves..."
TWASOpening word of "Jabberwocky"
TWAS"..... but the wind": Byron
TWAS"Jabberwocky" beginning
TWAS"... brillig..."
TWAS".. the night..."
TWAS".. the night ..."
TWASStart of a Christmas classic
TWAS".. brillig ...": "Jabberwocky" opening
TWAS".. brillig, and the slithy ...": Carroll
TWASChristmas classic opening
TWASChristmas or Carroll poem opening
TWASQuaint contraction
TWASSeasonal poem lead-in
TWAS"... the night before..."
TWASChristmas poem opener
TWAS"... brillig, and the slithy toves..." ("Jabberwocky")
TWAS"... the night before Christmas..."
TWASWord before "brillig"
TWAS"...... but the wind" (Lord Byron)
TWASMoore opener
TWASStart of a Christmas poem
TWASMoore poem starter
TWAS"... brillig ..."