The most common and most likely answer to this crossword clue is the 8 letter word BACKWASH
I've seen this crossword clue in The Daily Telegraph
B
A
C
K
W
A
S
H
More clues leading to the result BACKWASH
Buddy explains!
The straight part
We know that "Waves behind ship" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case waves behind ship = backwash.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 BACKWASH mean?
BACKWASH noun- The backward flow of water from oars or propeller or breaking waves.
- The similar flow of air from an aircraft engine.
- The result or consequence of an event; an aftermath.
- The saliva, spit or food particles that have flowed back into a drink after someone has drunk from it.
- To operate a water filter in the reverse direction in order to clean it.
- To affect with backwash.
- To clean the oil from wool after combing.