The most common and most likely answer to this crossword clue is the 8 letter word SKIPJACK
I've seen this crossword clue in The Guardian
S
K
I
P
J
A
C
K
More clues leading to the result SKIPJACK
- Fish container placed in front of sailor
- Fish with small sharp extremity almost turned on sailor
- Waste container and lifting mechanism getting a nut turned round?
- Fish pass over sailor
- Swimmer? She’s first to sleep with weightlifter
- Captain appearing with sailor’s fish
- Frisk a sailor to find tuna
- Leave out sailor’s fish
- Fish going straight from Queen to Number Ten?
- Cold-weather gear last two characters are lacking protects people initially – it’s for him
Buddy explains!

The straight part
We know that "a nut turned round" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a nut turned round = skipjack.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 SKIPJACK mean?
SKIPJACK noun- Any of several unrelated fish.
- An upstart.
- An elaterid; a click beetle.
- A shallow sailboat with a rectilinear or V-shaped cross section.