A phrase that combines a verb with a preposition or adverb or both and that functions as a verb whose meaning is different from the combined meanings of the individual words
Phrasal Verb:
clam up
Meaning:
to say nothing. (Closing one's mouth in the way that a clam closes up.)
Example:
The minute they got him in for questioning, he clammed up.
Phrasal verbs are multi-word verbs that, like single-word verbs, convey action of the body or mind or occurrences. Phrasal verbs consist of a basic verb + another word or words, usually a preposition or adverb. Example: speak (basic verb) + up (preposition)