The most common and most likely answer to this crossword clue is the 9 letter word SNOWBALLS
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More clues leading to the result SNOWBALLS
Buddy explains!

The straight part
We know that "Rockets" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case rockets = snowballs.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 SNOWBALLS mean?
SNOWBALLS noun- A ball of snow, usually one made in the hand and thrown for amusement in a snowball fight; also a larger ball of snow made by rolling a snowball around in snow that sticks to it and increases its diameter.
- A cocktail made from lemonade and advocaat.
- Something that snowballs (grows rapidly out of control).
- A sex act involving passing ejaculated semen from one person's mouth to another's.
- A type of ice dessert.
- A type of cake.
- To rapidly grow out of proportion or control.
- To play at throwing snowballs.
- To pelt with snowballs; to throw snowballs at.
- (sexual slang) To receive a man's ejaculate in one's mouth, and then to pass it back and forth between one's mouth and his.