The most common and most likely answer to this crossword clue is the 5 letter word SNELL
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More clues leading to the result SNELL
Buddy explains!

The straight part
We know that "Angler’s bit of gut" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case angler’s bit of gut = snell.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 SNELL mean?
SNELL adjective- Quick, smart; sharp, active, brisk or nimble; lively.
- Quick-witted; witty.
- Harsh; severe.
- A short line of horsehair, gut, monofilament, etc., by which a fishhook or lure is attached to a longer (and usually heavier) line.
- To tie a hook to the end of a fishing line with a snell knot.