The most common and most likely answer to this crossword clue is the 10 letter word UNDERCOVER
I've seen this crossword clue in The Daily Telegraph
U
N
D
E
R
C
O
V
E
R
More clues leading to the result UNDERCOVER
Buddy explains!

The straight part
We know that "Type of agent/having insurance" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case type of agent/having insurance = undercover.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 UNDERCOVER mean?
UNDERCOVER noun- A person who works undercover.
- To provide too little coverage.
- Performed or happening in secret.
- Employed or engaged in spying or secret investigation.