The most common and most likely answer to this crossword clue is the 7 letter word SALLIED
I've seen this crossword clue in The Daily Telegraph
S
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More clues leading to the result SALLIED
Buddy explains!

The straight part
We know that "ventured forth" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case ventured forth = sallied.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 SALLIED mean?
SALLIED verb- To make a sudden attack (e.g. on an enemy from a defended position).
- To set out on an excursion; venture; depart (often followed by "forth.")
- To venture off the beaten path.