The most common and most likely answer to this crossword clue is the 5 letter word START
I've seen this crossword clue in The Times
S
T
A
R
T
More clues leading to the result START
Buddy explains!

The straight part
We know that "new venture" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case new venture = start.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 START mean?
START noun- The beginning of an activity.
- A sudden involuntary movement.
- The beginning point of a race, a board game, etc.
- An appearance in a sports game, horserace, etc., from the beginning of the event.
- A young plant germinated in a pot to be transplanted later.
- An initial advantage over somebody else; a head start.
- To begin, commence, initiate.
- To begin an activity.
- To have its origin (at), begin.
- To startle or be startled; to move or be moved suddenly.
- To break away, to come loose.
- To put into play.
- To pour out; to empty; to tap and begin drawing from.
- To start one's periods (menstruation).
- A tail, or anything projecting like a tail.
- A handle, especially that of a plough.
- The curved or inclined front and bottom of a water wheel bucket.
- The arm, or level, of a gin, drawn around by a horse.