Are there any risk of bricking the macbook by cloning to a partition?
Certainly it is not safe (in my opinion) to resize without deleting the partition, which is the core part of your plan. 


  Clone the partition to a 32GB USB Flash drive using Clonezilla


I personally would clone from OSX to a Sata external drive.

So your plan appears okay, alebit I would do it differently: if you are happy consigning an operating system to USB. I think you have omitted one important point: to make sure you have a full Timemachine backup before deleting all other partitions except your Mac OSX. If your accidentally trash you Mac compartment, it is easily restored.



Timemachine is essential for this operation. If you don't have a TM backup, simply click Apple icon->System Preferences->Timemachine, then assign your backup disk. The backup will take hours for the first time, but is quick thereafter. It will only backup your OSX.



Resizing without deleting a disk
iPartition could perform resizing without deleting a disk, but its unsafe (definitely not recommended). If anything goes wrong my experience was you lose your entire harddrive. So yes you can do a resize without "bricking" (deleting) your Linux, personally I wouldn't risk it. You definitely need all drives backedup to do this. Note the company that does iPartition is no longer trading but the app is available free from July. However it does not work with Mojave (10.13 and below).

I don't know Clonezilla, but have used CCC (Carbon Copy cloner) which is good, but I think you pay for it now. I presume Clonzilla is free. 

I would do point 4. differently. 


Once you have cloned the disk you can use Go->Utilities->DiskUtilities and  "Restore" option to clone the Linux versions back onto their respective disks.
DiskUtilities use to have a cloning option (as well as a Restore option), I assume its still there somewhere, perhaps when you login via Recovery mode it 'appears'.