The most common and most likely answer to this crossword clue is the 7 letter word BREAKER
B
R
E
A
K
E
R
More clues leading to the result BREAKER
- . Wave Muppet Republican inside
- Mug appropriates ‘Republican wave’
- Damaging wave?
- Wave from food producer going round about
- The rest going ahead of the Queen, a smashing person
- Cup-holding king gives a wave
- At the end of a short holiday see Her Majesty wave
- Wave from demolition worker
- Wave of destruction?
- Quantity of water from river filling cup
Buddy explains!

The straight part
We know that "Quantity of water" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case quantity of water = breaker.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 BREAKER mean?
BREAKER noun- Something that breaks.
- A machine for breaking rocks, or for breaking coal at the mines
- The building in which such a machine is placed.
- A person who specializes in breaking things.
- (chiefly in the plural) A wave breaking into foam against the shore, or against a sandbank, or a rock or reef near the surface, considered a useful warning to ships of an underwater hazard
- A breakdancer.
- A user of CB radio.
- One who works in shipbreaking.
- A small cask of liquid kept permanently in a ship's boat in case of shipwreck.