The most common and most likely answer to this crossword clue is the 3 letter word TUB
I've seen this crossword clue in The Times
T
U
B
More clues leading to the result TUB
- Fast U-boat bags slow ship
- Brass instrument without a container
- VAT reduction in train
- Boat that's unwieldy however capsizes
- When inverted, only water could be in it
- Boat only goes backwards
- This boat unwieldy? Objection overturned
- VAT only goes up
- Slow boat merely capsized …
- Ungainly vessel nevertheless returned
Buddy explains!

The straight part
We know that "container" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case container = tub.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 TUB mean?
TUB noun- A flat-bottomed vessel, of width similar to or greater than its height, used for storing or packing things, or for washing things in.
- The contents or capacity of such a vessel.
- A bathtub.
- A slow-moving craft.
- Any structure shaped like a tub, such as a certain old form of pulpit, a short broad boat, etc.
- A small cask.
- Any of various historically designated quantities of goods to be sold by the tub (butter, oysters, etc).
- A box or bucket in which coal or ore is sent up a shaft.
- A sweating in a tub; a tub fast.
- A corpulent or obese person.
- To plant, set, or store in a tub.
- To bathe in a tub.