Thanks - the working solution:
SELECT Format(DateValue(DateStart),"dddd") AS DayOFWeek,
Count(Table1.DateStart) AS DayCount, Sum(IIf([PATIssuedYN]="Yes",1,))
FROM Table1 WHERE (((Table1.DateStart) Between DateAdd("d",-7,Now()) And Now()))
GROUP BY DateValue(DateStart);