via WordNet, Princeton University
be quiet, belt up, button up, close up, dummy up, keep mum, shut up
c-clamp, clamp, clean up, cleanup, climb, climb up, clomp, clump, colombia, colombo, columba, columbia, columbo, coulomb
via soundex() Hash Matches
Clam Up on Wikipedia
Clam Up on Wiktionary
Clam Up on Google
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the act of carrying something
leaky, tissue typing, casuist, et, rose periwinkle