The most common and most likely answer to this crossword clue is the 8 letter word BREACHED
I've seen this crossword clue in The Sunday Telegraph
B
R
E
A
C
H
E
D
Buddy explains!

The straight part
We know that "broke through" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case broke through = breached.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 BREACHED mean?
BREACHED verb- To make a breach in.
- To violate or break.
- (of the sea) To break into a ship or into a coastal defence.
- (of a whale) To leap out of the water.