The most common and most likely answer to this crossword clue is the 7 letter word PICKAXE
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More clues leading to the result PICKAXE
Buddy explains!
The straight part
We know that ", which may cause rocky break-up" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case , which may cause rocky break-up = pickaxe.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 PICKAXE mean?
PICKAXE noun- A heavy iron tool with a wooden handle; one end of the head is pointed, the other has a chisel edge.
- To use a pickaxe.