An idiom is defined as - a group of words whose meaning is different from the meanings of the individual words.
under the influence of (someone or something)
experiencing the effects of alcohol or drugs or a controlling power or person
The driver was under the influence of alcohol when he hit the young child. The woman is under the influence of her boss.
List of common idioms, their meanings and examples of their usage in sentences
An idiom is defined as - a group of words in a fixed order that has a particular meaning that is different from the meanings of each word on its own.