The most common and most likely answer to this crossword clue is the 3 plus 3 plus 3 plus 6 letter word FLY OFF THE HANDLE
I've seen this crossword clue in The Guardian
F
L
Y
O
F
F
T
H
E
H
A
N
D
L
E
More clues leading to the result FLY OFF THE HANDLE
- Lose one’s temper knowing of wretched thane held by force
- Get cross having to rush away before the opener
- Leave by plane: deal with article first, or lose it
- Suddenly leave the control and hit the roof
- Crewman’s in, knowing about foot and sore heel, to react angrily
- Get angry and quickly get away from other middle name
- Insect hovering around door maybe causing rage
- See red arch on holiday, then head out to take in lake
- Lose temper and take a plane then head out across lake
- Take a trip, getting high and het-up, then manage to lose it
Buddy explains!
The straight part
We know that "lose it" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case lose it = fly off the handle.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.