Reaction of alc. KOH with alkyl halide
The solvent used is a polar protic solvent which heavily solvates the OH- radical thereby decreasing it's nucleophilicity as the solvent forms a cage around the radical anion .Even though the basic strength of the anion is also decreased by solvation still the decrease in nucleophilicity is dominant as it is more difficult for a large solvated anion to attack at a carbon atom than to sneakily abstract an acidic hydrogen and hence the enolate is formed which then , proceeding through the SN NGP (neighbouring group participation) mechanism eliminates the Cl ion forming a cyclopropane.
Hope that this helps.