The most common and most likely answer to this crossword clue is the 5 letter word YO-YO
I've seen this crossword clue in The Guardian
Y
O
-
Y
O
More clues leading to the result YO-YO
- Lout repeatedly clipped child's toy
- Toy boy losing face — Joy too, both being rejected
- Child's toy bringing greetings from America
- More than one solver yet to finish? Child’s play, perhaps, using this
- Solvers who don’t finish go up and down
- Second person’s bottom pinched repeatedly – seen as source of fun?
- Repeatedly, you almost bounce up and down
- American version of ‘Allo ‘Allo! perhaps provides distraction for children
- Repeatedly calling for attention to toy
- Toy boy, not British, going up repeatedly
Buddy explains!

The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does YO-YO mean?
YO-YO noun- A toy consisting of a spheroidal or cylindrical spindle having a circular groove in which string is wound; it is used by holding the string in the fingers and reeling the spindle up and down by movements of the wrist.
- A volatile market that moves up and down.
- Someone who vacillates.
- A cloth rosette formed by gathering the outside edge of a circle of fabric in toward the centre using a running stitch.
- A foolish, annoying or incompetent person.
- To vacillate; to move up and down.