The most common and most likely answer to this crossword clue is the 15 letter word DIVERSIFICATION
I've seen this crossword clue in Financial Times
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Buddy explains!
The straight part
We know that "Branching out" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case branching out = diversification.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 DIVERSIFICATION mean?
DIVERSIFICATION noun- The act, or the result, of diversifying.
- A corporate strategy in which a company acquires or establishes a business other than that of its current product.
- An investment strategy involving investing in a range of assets with differing features in order to reduce specific risk.