The most common and most likely answer to this crossword clue is the 5 plus 5 letter word SMART MONEY
I've seen this crossword clue in The Daily Telegraph
S
M
A
R
T
M
O
N
E
Y
Buddy explains!
The straight part
We know that "clever investment" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case clever investment = smart money.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 SMART MONEY mean?
SMART MONEY noun- Experienced, well-informed investors, gamblers etc considered as a group.
- The money invested or bet by such people; by extension, the opinions of such people.
- Money paid by a person to buy himself off from some unpleasant engagement or some painful situation.
- Money allowed to soldiers or sailors, in the English service, for wounds and injuries received; also, a sum paid by a recruit, previous to being sworn in, to procure his release from service.
- Vindictive or exemplary damages; damages beyond a full compensation for the actual injury done.