The most common and most likely answer to this crossword clue is the 9 letter word ALLEVIATE
I've seen this crossword clue in The Daily Telegraph
A
L
L
E
V
I
A
T
E
More clues leading to the result ALLEVIATE
- Relax, with everything mostly consumed around six
- Ease a former son of Jacob snatched
- One recently has restricted terribly evil temper
- Make light of everyone having wandered naked
- Relieve patriarch in a recent case
- To mollify everyone, I’ve turned up and dined
- Temper shown when gangster, priest and troublemaker meet
- Moderate priest pursuing a line at end of service
- Leave it out — supporting a student’s ease?
- A vile tale about moderate
Buddy explains!

The straight part
We know that "Temper" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case temper = alleviate.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 ALLEVIATE mean?
ALLEVIATE verb- To make less severe, as a pain or difficulty.