Cluster vs. unclustered word combinations - what's the difference?

[Leximania]

What cluster/unclustered means? [URL removed] says, for e.g., that raise standard is a cluster but raise voice is unclustered combination. How a cluster is different from a non-cluster? Thank you if you find time to answer.

[emsr2d2]

What do "cluster" and "unclustered" means mean? [URL removed] says, for e.g. example, that raise standard is a cluster but raise voice is an unclustered combination. How is a cluster is different from a non-cluster?

Thank you if you find time to answer. Unnecessary. Thank us after we help you.

Welcome to the forum.

Doesn't the website you've been using explain the difference?