Also I am considering, that the size of the clam overgrew what RPi can handle - are there other RPi stakers here?
That seems possible. RPi is 32 bit right? My clam client (linux command line) after it has been running a while is using about 3.4 GB of address space though not quite that much actual memory. Seems close to a 32 bit limit. I'm on 64 bit system with plenty of RAM so it doesn't matter at all in my case but it may in yours.