Answer:

SURPRISE

AnswerCrossword Clue
SURPRISEParty announcement?
SURPRISEHaydn's "..." Symphony (Symphony No. 94 in G)
SURPRISEHaydn's 94th Symphony
SURPRISEBolt from the blue
SURPRISECatch off guard
SURPRISEAstonishment
SURPRISEParty type
SURPRISEStarting impetus
SURPRISEKind of party.
SURPRISEUnexpected pleasure.
SURPRISEBirthday-party word.
SURPRISEHaydn's "... Symphony"
SURPRISEParty line?
SURPRISEUnexpected gentleman is nosy, we hear (8)
SURPRISEWord shouted to start a party
SURPRISEChicago "Baby, What a Big ..."
SURPRISEWord yelled at some parties