Apple piercer saving son, William Tell’s father keeps child’s head up (7)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

A reversal (‘up’ in a down light) of an envelope (‘keeps) of C (‘ C hild’s head’) in ROS[s]INI (‘William Tell’s father’ – well, he was the author of the opera, with its famous overture) mnus an S (‘saving son’).