The most common and most likely answer to this crossword clue is the 5 letter word LOACH
I've seen this crossword clue in Independent
L
O
A
C
H
More clues leading to the result LOACH
- Fish, angler’s first in northern lake
- Catch British film maker
- Swimmer‘s trainer using lake instead of clubs
- Scholar at heart desperate to become a film director
- One sought on line taps an ISP from the east
- Fish, angler’s first to be caught in lake
- Area in Scottish lake for fish
- Film-maker, vile creature, changing sides
Buddy explains!

The straight part
We know that "Catch/British film maker" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case catch/british film maker = loach.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 LOACH mean?
LOACH noun- A bottom-feeding freshwater fish in the superfamily or suborder Cobitoidea.
- Acronym of light observation helicopter.