Answer: killer

AnswerCrossword Clue
KILLERVery demanding
KILLERAssassin
KILLERDifficult challenge, in slang
KILLERBear of a test
KILLERWord with giant or pain
KILLER"Totally awesome!"
KILLERRapacious whale.
KILLERGeraldine's boyfriend in Flip Wilson shows
KILLERWord with app or bee
KILLERWrestling legend Kowalski
KILLER.... whale
KILLER... whale
killerone that kills
killerone that kills (to put to death)