For those who want to know what the "limit" of the Combo meter is before trying or those who need some hints what helps to get this achievement a bit easier.

The current limit of the Combo meter is 999 and if you click one more the achievement triggers.
For the counter to raise you need to click the little pink petals falling down from the top of the screen.

So if you struggle there is a couple things that can make it easier.

• 1. You want to set the intensity of the "distractions" aka petals to "intense" this will greatly increase the amount of petals falling from the top of the screen.
  
  
  
  
• 2. You want to do this in a room with no cats as you will otherwise accidentially click on them or they grow up and this triggers a popup that will get in the way. Alternatively you can also turn on the new "Chill" mode to avoid the popups and cat info windows.
  (Thanks go to the comment section for highlighting this)
  
  
  
  
• 3. Pace yourself as frantic clicking will not help, you need to hit the petals and they move with different speeds and the achievement takes a while so make sure you can get there.
  
  
• 4. If you notice that the area you are currently focusing is not filling enough with more petals move to a different area where you see more petals. So move around but in a deliberate way not in panic to hit the next one.

Getting this achievement is also a great way to get some money early on.
The combo meter increases the amount of money you get per petal.

So with no combo meter you get around 0.01$
With a full meter of 999 you get 14.98$ per petal.

So I ended up with 10k I could spend on my first furniture and some extra cats.