The most common and most likely answer to this crossword clue is the 9 letter word STEENBRAS
I've seen this crossword clue in The Times
S
T
E
E
N
B
R
A
S
Buddy explains!
The straight part
We know that "It’s something in S Africa to catch" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case it’s something in s africa to catch = steenbras.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 STEENBRAS mean?
STEENBRAS noun- Any of various fish of the sparid genus Lithognathus.