The most common and most likely answer to this crossword clue is the 10 letter word HYPERSPACE
I've seen this crossword clue in The Times
H
Y
P
E
R
S
P
A
C
E
Buddy explains!
The straight part
We know that "An area of sci-fi" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case an area of sci-fi = hyperspace.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 HYPERSPACE mean?
HYPERSPACE noun- An n-dimensional Euclidian space with n > 3.
- A Euclidian space of unspecified dimension.
- A notional space orthogonal to the usual dimensions of space-time often used for faster-than-light travel.
- To travel or transport into hyperspace.