The most common and most likely answer to this crossword clue is the 9 letter word ROTOTILLS
R
O
T
O
T
I
L
L
S
Buddy explains!

The straight part
We know that "does some groundbreaking work" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case does some groundbreaking work = rototills.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 ROTOTILLS mean?
ROTOTILLS verb- To break up and turn soil using a rototiller.
- To make extensive and pervasive changes to a piece of code without altering its functionality.