I've found a solution - which is the simplest (maybe not the most elegant):

void f4(double b=0.77, void (*pfa)(double b, int &a)= [] (double b, int &a){
     a *= b;
}) {
    int a = 9;
    auto f = [pfa, b] (int &a) {pfa(b, a);};
    f(a);
}

https://wandbox.org/permlink/uKwqe1reWwwEJAGC