Do pioneering work, harrowing? (5,3,6)
I believe the answer is:
break new ground
I'm afraid I can't even guess how this answer relates to the clue.
Can you help me to learn more?
(Other definitions for break new ground that I've seen before include "multiple ways to indicate an anagram" , "how to innovate" , "Show innovation" , "Take your pick!" , "Start digging into" .)