It seems that I have a slight clicking from my rear mech.

It's not annoying loud and I can only hear it when riding next to parked cars or building (1m away) but not when "on the open road" so to speak (nothing solid adjacent to me ... like on a cycle path). I only notice it now because of the lack of other bike commuters as it's getting cold. Also, it only happens when I peddle and the chain gets pulled through.

I checked the drive line and it's straight and I don't think it's the need-to-adjust sound because the chains seems to be going through evenly.

Do all rear mechs make a slight sound, or is it the chain are this is where it bends the most?

Also, can I clean the mech without taking it off the bike?