Answer:

rider

AnswerCrossword Clue
RIDERDressage competitor
RIDERContract add-on
RIDERFare payer
RIDERBill tack-on
RIDERAmendment
RIDERBill add-on
RIDERPiece of pork?
RIDERHitchhiker
RIDERPassenger
RIDEROne in a habit
RIDEREquestrian
RIDERAddition to a bill
RIDERJockey
RIDERIt may be added to the bill
RIDERDocument amendment
RIDERBill attachment
RIDERAgreement adjustment
RIDERIt's added to the bill
RIDERLegislative postscript
RIDERBill addition
RIDERCodicil
RIDERFare
RIDERPolicy postscript