The most common and most likely answer to this crossword clue is the 10 letter word LAUNDROMAT
I've seen this crossword clue in The Times
L
A
U
N
D
R
O
M
A
T
Buddy explains!

The straight part
We know that "washer" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case washer = laundromat.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 LAUNDROMAT mean?
LAUNDROMAT noun- A self-service laundry facility with coin-operated washing machines, dryers, and sometimes ironing or pressing machines, open to the public for washing clothing and household cloth items.