Answer: discolor

AnswerCrossword Clue
DISCOLORBesmirch
DISCOLORBecome faded
DISCOLORTaint
DISCOLORStain.
DISCOLORTarnish
DISCOLORFade, maybe
DISCOLORRun in the wash, e.g.
discolorto alter the color of
discolorto change color