The most common and most likely answer to this crossword clue is the 7 letter word BATHTUB
I've seen this crossword clue in The Times
B
A
T
H
T
U
B
More clues leading to the result BATHTUB
- British city Metro, not entirely something you’d expect to fill with water
- Sailor turned up on time on hotel boat — a large vessel
- Where might one find bubbles? In a half of bubbly — fancy that!
- Objection raised after hotel bill returned for Jacuzzi?
- Temperature in small animal centre dips here, perhaps
- Be in centre, keeping time – be in hot water here?
- Home fixture for City, but needs to be arranged
- City bar rejected personal-hygiene equipment
- Where to come clean and boast what hubby occasionally sacrificed
- One enters this dirty city, only to come back
Buddy explains!

The straight part
We know that "something you’d expect to fill with water" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case something you’d expect to fill with water = bathtub.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 BATHTUB mean?
BATHTUB noun- A large container for holding water in which a person may bathe (take a bath).