  We study gravitational back-reaction within relational time formulations of
quantum mechanics by considering two versions of time: a time coordinate,
modelled as a global quantum degree of freedom, and the proper time of a given
physical system, modelled via an internal degree of freedom serving as a local
quantum "clock". We show that interactions between coordinate time and
mass-energy in a global Wheeler-DeWitt-like constraint lead to gravitational
time dilation. In the presence of a massive object this agrees with time
dilation in a Schwarzchild metric at leading order in $G$. Furthermore, if two
particles couple independently to the time coordinate we show that Newtonian
gravitational interaction between those particles emerges in the low energy
limit. We also observe features of renormalization of high energy divergences.
