stick up v.3
to hold one’s ground in an argument.
|Sl. and Its Analogues.|
to challenge, to oppose, esp. when one is ostensibly at a disadvantage.
|, ,||Sl. Dict.|
|Londinismen (2nd edn).|
|DSUE (1984) 1153: [...] coll.: from ca. 1840: dial. till ca. 1860, then coll.|