Accessing data in a closure?

What would be the minimal working example of that? This does not work, for example:

a = 2
f = x -> a*x
@show f(1).a

Maybe that is a good opportunity to understand how closures work a little further.

Edit:

This works:

f(a,x) = x -> a*x
@show f(1,2).a 

Yet the analogy with the OP example does not seem exact in this case.