A slang word used to describe female reproductive organs. The vagina, from the outside while shaved, could resemble a clam that is turned on it's side.
The ladies down the the screamin' peachwill wax your clam for $30.00.
(N.) Someone who is a pussy, ball less and sackless.
Billy I can't believe that bus full of hot broads came to your house and they all offered to be your sex slaves, and you said no. You're such a clam, and possibly a homo.