The most common and most likely answer to this crossword clue is the 7 letter word RENTIER
I've seen this crossword clue in The Daily Telegraph
R
E
N
T
I
E
R
More clues leading to the result RENTIER
Buddy explains!
The straight part
We know that "investor" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case investor = rentier.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 RENTIER mean?
RENTIER noun- An individual who receives an income, usually interest, rent, dividends, capital gains, or profits from his or her assets and investments.