Of course it's about connectivity.
It was argued that the word 'cluster', when defining a settlement area, rules out a straight line of settlements being counted as a Settlement area (i.e. they are not 'clustered').
That second interpretation sounds crazily impractical to define in any reasonable coherent way. E.g. is a U-shape "clustered"? Is a ring "clustered"? Is a pair of touching houses (a short line) not a cluster since it's also a straight line?