The most common and most likely answer to this crossword clue is the 12 letter word LONGSHOREMAN
I've seen this crossword clue in Financial Times
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Buddy explains!
The straight part
We know that "in the US as a port employee" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case in the us as a port employee = longshoreman.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 LONGSHOREMAN mean?
LONGSHOREMAN noun- A man employed to load and unload ships.
- One who makes a living along the shore by oyster-fishing, etc.