The most common and most likely answer to this crossword clue is the 8 letter word TRAWLING
I've seen this crossword clue in The Guardian
T
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Buddy explains!
The straight part
We know that "Boatman might try this to catch" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case boatman might try this to catch = trawling.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 TRAWLING mean?
TRAWLING verb- To take (fish or other marine animals) with a trawl.
- To fish from a slow-moving boat.
- To make an exhaustive search for something within a defined area.
- A commercial fishing technique in which a net is dragged by a moving boat.
- A laborious search.