More than one solver yet to finish? Child's play, perhaps, using this (2-2)
I believe the answer is:
yo-yo
'child's play perhaps using this' is the definition.
(yo-yo is a type of toy)
I can't explain the remainder of the clue.
(Other definitions for yo-yo that I've seen before include "Toy again in fashion" , "Toy consisting of a spool and string" , "Move up and down" , "-- - -- Ma, American cellist of Chinese/French origins" , "An up-and-down toy on a string" .)