end up +adj (最後成為) come in handy 這handy也是形容詞, 請問這是什麼文法,是怎麼來的?

Jeff gives 10 marks !
In grammar this is a clause. A clause (in grammar) is a group of words containing a subject and finite verb, forming a sentence Or part of a sentence, and often doing the work of a noun, adjective, or adverb . Different clauses include the dependent clause, independent clause, relative clause, subordinate clause. It's actually own separated and complete/in-complete in meaning.

In come in handy, the word handy means adj useful and simple to use :---a handy little gadget for machine-peeling potatoes---handy with her needle;good at sewing----The 7-11 shops are quite handy;------Keep a ballpen and paper handy;------Money may come in handy from my father;------Money come in handy;----Food come in handy------clothing come in handy(I open my own fashion shop !)End up a fashion show.

1. to end up（vi. + adv.） +補語 ＝eventually reach or come to a specified place, state, or course of action
If he carries on driving like that, he'll end up dead.
例句取自奇摩字典：
https://tw.dictionary.yahoo.com/dictionary?p=end+up
補語可以是名詞或形容詞等。上句的dead是「形容詞」

2. to come in handy = to come in useful
也是vi + adv. +補語
＝（在必要時）有用，派上用場
If something comes in handy, it is useful in a particular situation.
That key will come in handy if you lock yourself out.
The $20 check came in very handy.