The most common and most likely answer to this crossword clue is the 9 letter word MASTERING
I've seen this crossword clue in The Daily Telegraph
M
A
S
T
E
R
I
N
G
Buddy explains!
The straight part
We know that "Overcoming" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case overcoming = mastering.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 MASTERING mean?
MASTERING verb- To be a master.
- To become the master of; to subject to one's will, control, or authority; to conquer; to overpower; to subdue.
- To learn to a high degree of proficiency.
- To own; to possess.
- (especially of a musical performance) To make a master copy of.
- (usually with in) To earn a Master's degree.
- Becoming professional in the use of something; having mastery of.
- The process by which an audio recording is mastered.