Answer: inkspot

AnswerCrossword Clue
INKSPOT

A cappella group member

INKSPOT

1940s vocal quartet member

INKSPOT

Laundry challenge

INKSPOT
Result of a leaky pen
INKSPOT
"If I Didn't Care" group member
INKSPOTStain.
INKSPOTIvory Watson or Charlie Fuqua, e.g.
INKSPOTPen user's stain