I've got a sentence
Good people get up ______
Could I use "Early in the morning " ? Is it a Clause?
The answer given is
"when the sun rises"?
Please tell which one is correct or both? Also, please explain why. Thank you.
A clause should contain subject and predicate, either explicit or implicit.
He wants [to go to the circus].
TO-infinitive clause - to go to the circus. It's a clause because it contains an implicit Subject - he, Predicator - go and Complement - to the circus. Subject - he and Predicate - go to the circus. That to can be regarded as a subordinator.
It's possible [for him to jump over the wall].
Here the TO-infinitive clause has an explicit subject -him.
But your early in the morning is not a clause. It lacks a subject and a predicator. It, however, can be analyzed as a phrase.
early is an adverb and it's a head-word. And it takes a Preposition Phrase (PP) as a post-modifier. so early in the morning is an Adverb Phrase (AdvP).
In your sentence -
Good people get up [early in the morning].
The AdvP acts as a temporal adjunct. You can also use a clause there instead of that AdvP. A good choice is, as Cardinal suggested in his comment, when the sun rises.