The most common and most likely answer to this crossword clue is the 6 letter word DOCKER
I've seen this crossword clue in Financial Times
D
O
C
K
E
R
Buddy explains!
The straight part
We know that "Pier worker" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case pier worker = docker.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 DOCKER mean?
DOCKER noun- One who performs docking, as of tails.
- A dockworker.