The most common and most likely answer to this crossword clue is the 8 letter word WATERWAY
I've seen this crossword clue in The Times
W
A
T
E
R
W
A
Y
More clues leading to the result WATERWAY
Buddy explains!

The straight part
We know that "Canal maybe" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case canal maybe = waterway.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 WATERWAY mean?
WATERWAY noun- A body of water, such as a river, channel or canal, that is navigable.
- A conduit or watercourse, such as on the deck of a ship, to drain water.