The most common and most likely answer to this crossword clue is the 4 letter word CHAR
I've seen this crossword clue in The Times
C
H
A
R
More clues leading to the result CHAR
Buddy explains!

The straight part
We know that "cleaner" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case cleaner = char.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 CHAR mean?
CHAR noun- A charred substance.
- To burn something to charcoal.
- To burn slightly or superficially so as to affect colour.
- One of the several species of fishes of the genus Salvelinus.
- A charred substance.
- One of the several species of fishes of the genus Salvelinus.
- A time; a turn or occasion.
- A turn of work; a labour or item of business.
- An odd job, a chore or piece of housework.
- A charlady, a woman employed to do housework; cleaning lady.
- To turn, especially away or aside.
- To work, especially to do housework; to work by the day, without being a regularly hired servant.
- To perform; to do; to finish.
- To work or hew (stone, etc.).
- A character (text element such as a letter or symbol).
- Tea, sometimes specifically masala chai
- Synonym of Korean foot: a traditional unit of length equivalent to about 30.3 cm.