I disagree with comments claiming that sense in the cited text means meaning. If that were the case, it would be completely unnecessary to include the words this sense of at all...
1: It1 is mutual interaction or inter-dependence for a common purpose which distinguishes the members of a group from a mere aggregation of individuals.
...which can be simplified and rephrased to...
2: Mutual interaction distinguishes the members of a group from a mere aggregation of individuals.
I find that perfectly valid as it stands, but we can explicitly try out both possible interpretations of sense as...
2a: A [shared] feeling of mutual interaction distinguishes the members of a group from a mere aggregation of individuals.
...and...
2b: The meaning [of] "mutual interaction" distinguishes the members of a group from a mere aggregation of individuals.
Where I think 2b is nonsense.
1 This is the "existential it" as in It's raining. It doesn't refer to a specific thing, any more than there in There's nothing more to say refers to a specific place.