The reaction,  $3{\mathrm{ClO}}_{\left(\mathrm{aq}\right)}^{-}\to {\mathrm{ClO}}_{3\left(\mathrm{aq}\right)}^{-}+2{\mathrm{Cl}}_{\left(\mathrm{aq}\right)}^{-}$ is an example of 

In the given reaction, the oxidation state of the chlorine atom changes from $+1\left(\text{ in }{\mathrm{ClO}}^{-}\right)$ to + 5 $\text{ (in }{\mathrm{ClO}}_3^{-}\text{) }$ and $-1\left(\text{ in }{\mathrm{Cl}}^{-}\right)$ This means that chlorine is getting oxidized as well as reduced. Such reactions are called disproportionation reactions.