sometimes when i sidechain a sustained bass part to a kick drum i can hear a clicky sound coming through where the kick is hiting, any idea how to get rid of this?
Adjust your attack.
yeah if you are using the ableton compressor and you are getting the click sound switch the “Model” set at the bottom to FF1 you’ll find in most cases this will stop it.
hitting ff1 seemed to clear it up mostly as oddly enough there was still a clicky sound coming from the sylenth even with the compressor turned off, so i programmed a new bass and it dissapeared :S
sylenth admits clicks when you have zero attack or zero release, if you lift the attack any release by even 0.5 the click will go.
this is usually very noticeable when using the modulation on the filter 
thanks for the tip man