LTSpice common emitter amplifier distortion
Transistor amplifiers always have a certain amount of distortion, since the amplifying devices are nonlinear. In this case the current through the transistor depends exponentially on the input voltage.

A smaller signal will exhibit less distortion, so reducing the amplitude could be a first step. To ensure a proper operating point the output signal should be probed at the collector of Q1.

For a further reduction of the distortion feedback is required, which in this case could be a simple emitter resistor.

Feedback decreases distortion but decreases the gain as well. A multistage amplifier with global feedback could be used, but an opamp based design is usually easier and offers good performances since a large gain is available for feedback.