The most common and most likely answer to this crossword clue is the 7 letter word INBOARD
I've seen this crossword clue in The Daily Telegraph
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N
B
O
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More clues leading to the result INBOARD
Buddy explains!

The straight part
We know that "contained by ship" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case contained by ship = inboard.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 INBOARD mean?
INBOARD noun- An engine located within the hull of a ship
- A boat with such an engine
- To discount a product in order to increase sales
- Within a ship
- Nearer the hull (as opposed to outboard)