The most common and most likely answer to this crossword clue is the 7 letter word PLANETS
I've seen this crossword clue in Financial Times
P
L
A
N
E
T
S
Buddy explains!
The straight part
We know that "Worlds beyond earth" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case worlds beyond earth = planets.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 PLANETS mean?
PLANETS noun- Each of the seven major bodies which move relative to the fixed stars in the night sky—the Moon, Mercury, Venus, the Sun, Mars, Jupiter and Saturn.
- A body which orbits the Sun directly and is massive enough to be in hydrostatic equilibrium (effectively meaning a spheroid) and to dominate its orbit; specifically, the eight major bodies of Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. (Pluto was considered a planet until 2006 and has now been reclassified as a dwarf planet.)
- A large body which directly orbits any star (or star cluster) but which has not attained nuclear fusion.
- In phrases such as the planet, this planet, sometimes refers to the Earth.