An electron, indeed any particle, is neither a particle nor a wave.
Describing the electron as a particle is a mathematical model
 that works well in some circumstances while describing it as a wave
  is a different mathematical model that works well in other circumstances.
When you choose to do some calculation of the electron's behaviour that treats it
 either as a particle or as a wave, you're not saying the electron is a particle or is a wave:
  you're just choosing the mathematical model that makes it easiest to do the calculation.