I think this would be the answer because a grammatical name is the name given to a word, phrase or clause depending on its function in a given clause or sentence. There are several grammatical names such as noun phrase, adverbial phrase, adjective phrase, adjectival phrase, prepositional phrase, noun clause, adverbial clause and adjectival/relative clause. In this case i think the grammatical name is a clause meaning it has a subject and verb "man" being the subject and "understood" being the verb.
[uncountable, countable] thought (of something/of doing something) an intention or a hope of doing something She had given up all thought of changing her job.
