The following code should return the clusters that have hosts connected to a specific vdSwitch
$tgtVDS="MyVDS"
$vds=Get-VDSwitch|where {$_.Name-eq$tgtVDS}$esxNames=@()$vds.ExtensionData.Config.Host|%{ $esxNames+=Get-View$_.Config.Host|Select-ExpandPropertyName
}Get-VMHost-Name$esxNames|Get-Cluster|SelectName