The most common and most likely answer to this crossword clue is the 4 letter word SNIB
S
N
I
B
More clues leading to the result SNIB
Buddy explains!

The straight part
We know that "catch" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case catch = snib.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 SNIB mean?
SNIB noun- A latch or fastening for a door, window etc.
- A reprimand; a snub.
- To latch (a door, window etc.).