clam up

1 definition found

clam up - WordNet (r) 2.1 (2005) :

  clam up
      v 1: refuse to talk or stop talking; fall silent; "The children
           shut up when their father approached" [syn: close up,
           clam up, dummy up, shut up, belt up, button up,
           be quiet, keep mum] [ant: open up]