The most common and most likely answer to this crossword clue is the 7 letter word FLIPPED
I've seen this crossword clue in The Guardian
F
L
I
P
P
E
D
Buddy explains!

The straight part
We know that "lost it" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case lost it = flipped.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 FLIPPED mean?
FLIPPED verb- To throw so as to turn over.
- To put into a quick revolving motion through a snap of the thumb and index finger.
- To win a state (or county) won by another party in the preceding elections
- To turn state's evidence; to agree to testify against one's co-conspirators in exchange for concessions from prosecutors.
- To induce someone to turn state's evidence; to get someone to agree to testify against their co-conspirators in exchange for concessions.
- To go berserk or crazy.
- To buy an asset (usually a house), improve it and sell it quickly for profit.
- To invert a bit (binary digit), changing it from 0 to 1 or from 1 to 0.