___ chowder (4)
I believe the answer is:
clam
'chowder' is the definition.
(clam chowder is a kind of chowder)
This is the entire clue.
(Other definitions for clam that I've seen before include "Shellfish - secretive person" , "One is as uncommunicative as a mollusc" , "Secretive person - mollusc" , "ringing noise produced by > very reticent type" , "Burrowing marine mollusc living in sand or mud" .)