Best to get this on lower levels. You need to build a pattern which allows you to pop the middle segment, an dthen the rest all collapse around it. If you set up a colour patter like:
BBGGYYRRBBRRBRYGB
Then pop a Red ball in the middle where I've marked the bold RR:
BBGGYYRRBBRRBRYGB
The set of threes will blow up one after the other as follows:
BBGGYYRRBBBRYGB
BBGGYYRRRYGB
BBGGYYYGB
BBGGGB
BBB
Achievement unlocked!
All the best!
- Iain