Answer: smutch

AnswerCrossword Clue
SMUTCHSoiled spot
SMUTCHSmudge.
SMUTCHBlacken, as with soot.
SMUTCHBlot.
SMUTCHGrime
smutchto smudge or soil
smutchsmudge or stain
smutchdirt, grime, or smut
smutchto smudge (to smear (to spread with something oily or sticky))