The most common and most likely answer to this crossword clue is the 10 letter word INSTIGATOR
I've seen this crossword clue in The Times
I
N
S
T
I
G
A
T
O
R
Buddy explains!
The straight part
We know that "I go in and start, somehow" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case i go in and start, somehow = instigator.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 INSTIGATOR mean?
INSTIGATOR noun- A person who intentionally instigates, incites, or starts something, especially one that creates trouble.