Clayton, 23, was selected in the seventh round of the NFL draft despite having never played a game of American football.
Burnley say they have been informed about “offensive footage” on social media from some of their travelling supporters on Saturday afternoon.
At half-time, Aston Villa thought they had one foot in the Champions League. But by the end of a chaotic game against Chelsea, the Midlands club were relieved to take just another point towards a top-four place.