The most common and most likely answer to this crossword clue is the 6 letter word RETROS
R
E
T
R
O
S
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 = retros.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 RETROS mean?
RETROS noun- Past fashions or trends.
- A small rocket engine on a larger rocket or spacecraft, designed to slow or reverse its motion.
- An exhibition of works from an extended period of an artist's activity.