I tried stubbornly:

```
marg_combos_2 <- sapply(marg_combos[[3]],"[[", 'p.value') %>% as.data.frame()
sapply(marg_combos[[3]],"[[", 'p.value', drop=FALSE)
marg_combos_3 <- cbind(marg_combos, marg_combos_2)
colnames(marg_combos_3$.) <- "P_values_extracted"
names(marg_combos_3)
colnames(marg_combos_3)[which(names(marg_combos_3) == ".")] <- "P_values_extracted"
marg_combos_4 <- marg_combos_3 %>% select(1,2,4)
marg_combos_4 %>%
rowwise() %>%
mutate_if(is.list, ~paste(unlist(.), collapse = '|')) %>%
write.csv('marg_combos_4_final.csv', row.names = FALSE)
```

Key to the solutions was this:

```
marg_combos[[3]],"[[", 'p.value'
```

I have done it by many trial and error attempts.

And then in Excel straightaway:

Maybe someone could propose a simpler solution or with purrr more efficient one ?

I was stuck a bit when it came to get to a deeper elements of nested list.