take up for (someone or something)
To show one's support for someone or something; to provide help or assistance to someone or something. A man on the bus took up for the driver when a woman began screaming at him for being behind schedule. My father-in-law and I don't get along very well, but it meant a lot to me that he took up for me like that.
take up for
Support in an argument, as in To our surprise her father took up for her fiancé. [Second half of 1800s]
take up for
To support (a person or group, for example) in an argument.