Clamming up and Hard-hearted

Hard-hearted and clamming up are semantically related. In some cases you can use "Hard-hearted" instead an adjective "Clamming up".

Hard-hearted adjective - Having or showing a lack of sympathy or tender feelings.

Clamming up and hard-hearted are semantically related. Sometimes you can use "Clamming up" instead an adjective phrase "Hard-hearted".