The most common and most likely answer to this crossword clue is the 10 letter word HOBBYHORSE
I've seen this crossword clue in Financial Times
H
O
B
B
Y
H
O
R
S
E
Buddy explains!

The straight part
We know that "toy" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case toy = hobbyhorse.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 HOBBYHORSE mean?
HOBBYHORSE noun- The Irish hobby, an extinct breed of horse.
- A child's toy consisting of a (usually wooden or cloth) horse's head mounted on a stick.
- A topic about which someone loves to talk at great length.
- A puppet-like costume used in some traditional dances and festivals that gives its wearer the appearance of a man on horseback.
- An early bicycle with no pedals or brakes; a draisienne.