The most common and most likely answer to this crossword clue is the 7 letter word PRIVIES
I've seen this crossword clue in Financial Times
P
R
I
V
I
E
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 = privies.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 PRIVIES mean?
PRIVIES noun- An outdoor facility for urination and defecation, whether open (latrine) or enclosed (outhouse).
- A lavatory: a room with a toilet.
- A toilet: a fixture used for urination and defecation.
- A partaker; one having an interest in an action, contract, etc. to which he is not himself a party.