How can I detect a word in a column variable and mutate it in a new column in R using dplyr?

I have a data frame that looks like this :

and I want to look like this :

How can I do this in R ?

library(tidyverse)
var = c("A_CAT","B_DOG","A_CAT","F_HORSE","GEORGE_DOG","HeLeN_CAT")
df = tibble(var);df

>Solution :

df %>%
   mutate(var_new = str_remove(var, '.+_'))

# A tibble: 6 × 2
  var        var_new
  <chr>      <chr>  
1 A_CAT      CAT    
2 B_DOG      DOG    
3 A_CAT      CAT    
4 F_HORSE    HORSE  
5 GEORGE_DOG DOG    
6 HeLeN_CAT  CAT