Zach Mitchell feels he has "unfinished business" at St Johnstone after returning for a second spell on loan from Charlton Athletic. The 21-year-old defender started last season on loan at Hibernian but was recalled by the Championship club in January after having made only two appearances. Mitchell had joined St Johnstone the previous February and played 10 times, seven of them starts, as the Perth side suffered relegation from the Scottish Premiership.