The most common and most likely answer to this crossword clue is the 5 letter word MOUTH
M
O
U
T
H
More clues leading to the result MOUTH
- Insect eats uniform with this
- Cheek, or something close to it
- Spokesperson‘s unwelcome in the outskirts of Middlesbrough
- Light aeroplane conveying unionist spokeswoman
- Master at a loss with hard insolence
- Potential diner making a wry face
- Speaker’s boastful talk
- Nun maybe accepts university entrance
- Say something dumb
- One hears word of it
Buddy explains!

The straight part
We know that "insolence" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case insolence = mouth.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 MOUTH mean?
MOUTH noun- The opening of a creature through which food is ingested.
- The end of a river out of which water flows into a sea or other large body of water.
- An outlet, aperture or orifice.
- A loud or overly talkative person.
- (saddlery) The crosspiece of a bridle bit, which enters the mouth of an animal.
- A principal speaker; one who utters the common opinion; a mouthpiece.
- Cry; voice.
- Speech; language; testimony.
- A wry face; a grimace; a mow.
- To speak; to utter.
- To make the actions of speech, without producing sound.
- To utter with a voice that is overly loud or swelling.
- To pick up or handle with the lips or mouth, but not chew or swallow.
- To take into the mouth; to seize or grind with the mouth or teeth; to chew; to devour.
- To form or cleanse with the mouth; to lick, as a bear licks her cub.
- To make mouths at.