String toys (2-3)
I believe the answer is:
yo-yos
'string toys' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for yo-yos that I've seen before include "Moves up and down" , "1930s spinning toys" , "Up-and-down toys on string" , "Toy with spool and string" , "Toys with pair of joined discs and string" .)