The most common and most likely answer to this crossword clue is the 7 letter word SEE-SAW
I've seen this crossword clue in The Guardian
S
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More clues leading to the result SEE-SAW
Buddy explains!
The straight part
We know that "Yo-yo" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case yo-yo = see-saw.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.
Crossword Answer definitions
SEE-SAW noun- A structure composed of a plank, balanced in the middle, used as a game in which one person goes up as the other goes down.
- A series of up-and-down movements.
- A series of alternating movements or feelings.
- To use a seesaw.
- (by extension) To fluctuate.
- To cause to move backward and forward in seesaw fashion.