It's a Joule Thief type oscillator to generate a DC output from a single alkaline cell.
Works in LTspice (below):
Spice normally does a DC bias calculation before it does the transient response, which causes the oscillator circuit to then end up in a quasi-stable steady DC state with no oscillations.
You need to prevent that initial bias calculation by using the
uic (Use Initial Conditions) command, or whatever command stops that calculation in Proteus.
View attachment 145363