I think it depends on the clique. If it exists for the self-grandizement of members and puts down non members then it's negative.
But if it's inclusive of anyone who wants to join and supportive it can be helpful. For example, in high school, I belonged to what could have been called a clique - we were the school's smart social misfits. We claimed a corridor of the school as "our" space an hung out there at lunch and on spares, we welcomed anyone who was into philosophy or poetry or theater or debating or politics, basically anything intellectual that didn't fit with the majority of the student interests. But anyone was welcome at any time and we didn't knock non members. For me it helped me make it through high school.
But there were definitely cliques in high school that put down non-members and I'd say they were unhealthy.
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"I danced in the morning when the world was begun. I danced in the moon and the stars and the sun". From my favourite hymn.
"If you see the wonder in a fairy tale, you can take the future even if you fail." Abba