The most common and most likely answer to this crossword clue is the 8 letter word RESEARCH
I've seen this crossword clue in The Daily Telegraph
R
E
S
E
A
R
C
H
More clues leading to the result RESEARCH
- Carer she misled in fact-finding
- Touching address finally by head of Europol leading investigation
- Carry out investigation about vital organ in school
- Look into touching prior to examination
- Cars here to be broken in systematic investigation
- Look into carer, she must be shattered
- Study to restore cut-down monument
- Investigation after soldiers brand companion
- Soldiers cauterise companion in investigation
- Burn companion again for investigation
Buddy explains!

The straight part
We know that "investigation" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case investigation = research.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 RESEARCH mean?
RESEARCH noun- Diligent inquiry or examination to seek or revise facts, principles, theories, applications, etc.; laborious or continued search after truth.
- A particular instance or piece of research.
- To search or examine with continued care; to seek diligently.
- To make an extensive investigation into.
- To search again.