Answer: sneakier

AnswerCrossword Clue
SNEAKIERMore deceitful
SNEAKIEREven more furtive
SNEAKIERMore underhanded
SNEAKIERStealthier.
SNEAKIERMore furtive.
SNEAKIERMore furtive
sneakierlike or suggestive of a sneak; furtive; deceitful
sneakierSNEAKY, deceitful