The most common and most likely answer to this crossword clue is the 5 letter word JOHNS
I've seen this crossword clue in The Guardian
J
O
H
N
S
Buddy explains!

The straight part
We know that "cans" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case cans = johns.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 JOHNS mean?
JOHNS noun- A prostitute's client.
- A device or place to urinate and defecate: now usually a toilet or lavatory, but also a chamber pot or outhouse.
- A Western man traveling in East Asia.
- A male mule.