The most common and most likely answer to this crossword clue is the 6 plus 9 letter word INSECT REPELLENT
I
N
S
E
C
T
R
E
P
E
L
L
E
N
T
More clues leading to the result INSECT REPELLENT
- Sleeper in tent with 150 flies around? You need this!
- It deters pest during school dance, in which piano is fast
- Flies driver away from edges of seismal epicentre, moving fast
- Debugging tool?
- Flies undone by this?
- The cause of flies being left undone?
- Elected group about to strike with new toxic spray
- Fly away after using this spray?
- Might it create a no-fly zone?
Buddy explains!
The straight part
We know that "It deters pest" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case it deters pest = insect repellent.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.