Uncommunicative creature? (4)
I believe the answer is:
clam
'creature?' is the definition.
(clam is a kind of animal)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for clam that I've seen before include "Quahog" , "shy person" , "reticent person" , "Burrowing marine mollusc living in sand or mud" , "Proverbially reticent marine mollusc" .)