Help - filtering data that has functions performed

I'm trying to filter this code set
TITANIC %>% group_by(pclass, sex, survived) %>% summarise(avg = mean(age, na.rm = TRUE))

I want the table to only show me survivors. I can't seem to figure out how to filter data that's already had functions performed on it.

its exactly the same filter whether it has or hadn't had functions performed on it; the way you are asking for help implies you would know how to filter a dataset normally,... so just do what you would have done here

I get this issue when I try to filter
summarise() has grouped output by 'pclass', 'sex'. You can override using the .groups argument.summarise() has grouped output by 'pclass', 'sex'. You can override using the .groups argument.summarise() has grouped output by 'pclass', 'sex'. You can override using the .groups argument.Error in filter(sex == "yes") : object 'sex' not found

please show your code