Answer:

onceinalifetime

Answer	Crossword Clue
ONCEINALIFETIME	Very rare
ONCEINALIFETIME	Type of opportunity
ONCEINALIFETIME	Ultrarare

ONCEINALIFETIME	Hit play of 1930.
ONCEINALIFETIME	Kaufman-Hart play.
ONCEINALIFETIME	Designating a unique event.
ONCEINALIFETIME	Rare
ONCEINALIFETIME	Infrequently
ONCEINALIFETIME	Play about Hollywood
ONCEINALIFETIME	Kaufman-Hart play
ONCEINALIFETIME	Never? Well, almost

ONCEINALIFETIME	Seldom, and then some
ONCEINALIFETIME	Slightly more than never
ONCEINALIFETIME	Kaufman-Hart play: 1930
ONCEINALIFETIME	Hardly ever
ONCEINALIFETIME	Very unusual
ONCEINALIFETIME	Rarely
ONCEINALIFETIME	Bricusse-Newley song: 1961
ONCEINALIFETIME	Like certain opportunities

ONCEINALIFETIME	Extremely rare
ONCEINALIFETIME	Very rarely indeed
ONCEINALIFETIME	Talking Heads' "As the days go by, let the water hold me down" song
ONCEINALIFETIME	Like opportunities that might be hard to decline