How to calculate the ICC (intra-class correlation coefficient) from a coxme() object

Question

For model:

fit1 <- coxme(Surv(time, status) ~ age + sex + (1|area), data=df)

I need to calculate the ICC which is the random effect variance / (random effect variance + residual variance). I can see the random effect variance in the output of summary(fit1), but where is the residual variance? Or is there a simpler way of calculating the ICC?