Emitter Follower Output
You need to connect R2 to a negative supply voltage with enough headroom for your signal, or bias the input waveform so that it doesn't clip.

The output voltage an emitter-follower is usually V_out = V_in - 0.7V, but there are bounds on where this function works. For the expected behavior, VCC + 0.7V &gt; V_in &gt; VEE + 0.7V must be maintained, where VEE is your negative supply. In your case, VEE is equal to 0V since you don't have a negative supply. When your input voltage swings below 0.7V, the transistor turns off, and your output stays at the negative voltage rail.

Modify these lines to add in a negative power supply.

R2  4 5 3.3k
Vee 0 5 DC 15


Modify this line to bias the sine wave for the existing circuit.

Vin 1 0 SIN(7.5 5 60) dc 0