Here's a breakdown of the meaning:
* Insult: A rude or offensive remark or action.
* To: Indicates the direction or target of the insult.
Examples:
* "His behavior was an insult to the entire family." (His behavior was offensive to the family.)
* "The graffiti on the war memorial was an insult to the veterans who fought for our country." (The graffiti was offensive to the memory of veterans.)
* "That cheap plastic trophy was an insult to the winner's hard work and dedication." (The trophy was disrespectful to the winner's efforts.)
In essence, "insult to" means something that diminishes the worth, respect, or dignity of the target.