Brake booster
i bought a 12" section of hose at autozone, uncapped the oil fill, pulled the PCV hose off the intake, connected the autozone hose to the intake and used that as my seafoam hose.
back to your question...the clamp you are speaking of should have two little tabs facing one direction and one facing the opposite. you need to squeeze the tabs so that all three of them come together and the clamp loosens.

