The most common and most likely answer to this crossword clue is the 6 letter word TERROR
I've seen this crossword clue in The Times
T
E
R
R
O
R
More clues leading to the result TERROR
- Slips into lorry, stammering in panic
- Dread the ultimate in government failure
- Monkey’s mistake, sheltering under tree top
- Blunder into rocky peak, provoking panic
- Youngster causing havoc finally shot by mistake
- White’s fourth blunder creates consternation
- The next reign after Louis XVI?
- Fear defeat, ultimately by an own goal
- Earth yielding area with gold, a real handful
- Tearaway ultimately at fault
Buddy explains!

The straight part
We know that "in panic" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case in panic = terror.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 TERROR mean?
TERROR noun- Intense dread, fright, or fear.
- The action or quality of causing dread; terribleness, especially such qualities in narrative fiction.
- Something or someone that causes such fear.
- Terrorism