Departing child makes mischief (6-2)
I believe the answer is:
goings-on
'mischief' is the definition.
(I've seen this before)
'departing child' is the wordplay.
'departing' becomes 'going' ('go' can be a synonym of 'depart').
'child' becomes 'son' (male child).
'going'+'son'='GOINGS-ON'
'makes' is the link.
(Other definitions for goings-on that I've seen before include "Suspect events or behaviour" , "Suspicious happenings" , "Activities, esp. dubious ones" , "mischief" , "Hanky-panky" .)