You didn't give us the fieldnames you wanted. So I'm going to guess you want them as 'thing1', 'thing2', 'thing3', etc. and assign the name in a loop. You can substitute your desired fieldname instead of these.
for i=1:length(Cluster_split)
myValue = Cluster_split{i};
myFieldname = ['thing' num2str(i)];
myStruct.(myFieldname) = myValue;
end
You can now inspect the structure:
myStruct.thing1
myStruct.thing23
