The entry for phrasal, adj. contains a brief explanation, but a dictionary isn’t quite the right resource for this.
phrasal verb n. a multi-word verb consisting of a verb and another element (typically an adverb or preposition) which together function as a single syntactical unit, as break down, make up, take out, see to, etc.
The OED does not distinguish phrasal verbs from regular verbs in the text, so there’s no way that I know of to search specifically for phrasal verbs.
I’d suggest something like Tom McArthur’s Concise Oxford Companion to the English Language or a good grammar manual for a more complete description and more examples.