The most common and most likely answer to this crossword clue is the 7 letter word SOLOMON
I've seen this crossword clue in The Times
S
O
L
O
M
O
N
More clues leading to the result SOLOMON
- King's indication of approval perhaps for something in garden?
- He built the Temple of Jerusalem unassisted, the first of seven?
- Wise man taking flight alone on Monday
- Unaccompanied male operating, a wise man
- Wise king on his own one day?
- Part of 24’s issue, having single-handedly taken on follower of Sun
- Man noted for his song, unaccompanied, this writer’s French
- Scottish man going it alone; was he wise?
- Wise king alone with Scottish man
- Old king alone a short while with knight
Buddy explains!

The straight part
We know that "He built the Temple of Jerusalem" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case he built the temple of jerusalem = solomon.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.