library(dplyr)
df <- data.frame(column=c(1,2,3))

column_string <- "column"
variable <- enquo(column_string)
print(variable)

<quosure>
  expr: ^"column"
  env:  empty

df %>% summarise(mean=mean(!! variable))

mean
1   NA
Warning message:
In mean.default(~"column") :
  argument is not numeric or logical: returning NA