The most common and most likely answer to this crossword clue is the 10 letter word RESEARCHER
I've seen this crossword clue in The Guardian
R
E
S
E
A
R
C
H
E
R
More clues leading to the result RESEARCHER
- Investigator dealing with Home Counties radio serial briefly
- Investigator is more cunning following short break and drug
- Her career’s varied, as analyst
- One investigating upcoming series on English peer
- Dodgy seer and novelist peer who conducts study
- One unearthing facts about brand used by singer/actress
- Her career’s ruined as analyst
- One who may discover her career’s ruined
Buddy explains!

The straight part
We know that "Investigator" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case investigator = researcher.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 RESEARCHER mean?
RESEARCHER noun- One who researches.