An idiom is defined as - a group of words whose meaning is different from the meanings of the individual words.
Idiom:
do (someone's) bidding
Meaning:
to do what someone else wants
Example:
The principal was able to get the head teacher to do his bidding with the other teachers.
List of common idioms, their meanings and examples of their usage in sentences
An expression in the usage of a language that is peculiar to itself either in having a meaning that cannot be derived from the conjoined meanings of its elements or in its grammatically atypical use of words.