What is a clause

 WHAT IS A CLAUSE

DEFINITION: A clause is a group of words with a finite verb, forming part of the sentence.
Note: The major difference between the phrase and the clause is the finite and non finite form of their verb.  therefore if a sentence doesn’t posess the characteristics of non finite verb, then it is a clause, but if it does it is a phrase. 
  There are two major types of classes which are the main or independent clause and the subordinate or dependent clause.

MAIN CLAUSE: This can stand in it own to make a complete sense or meaning in a sentence. examples
1. I am going home now
2.the choir came and ministered.

SUBORDINATE CLAUSE: It is a group of words, it always have a finite verb. it does not express a complete thought. in the sense that it needs the presence of the main clause to make a complete sentence.
examples of subordinate clauses are 
1. As soon as the boy saw the teacher, he took to his heels.
2. Unless he passes the examination, he will not travel abroad.
3.How he knew my name still remains a history.
4.The landlord whose house was burgled has reported to the police.

TYPES OF SUBORDINATE CLAUSES
There are three types of subordinate clauses, namely: noun clause, relative clause, and adverbial clause.

(a). NOUN CLAUSE: A noun clause performs the same grammatical functions as nouns and noun phrases. these functions are;
1.subject of the verb 
2.subject complement
3.object of the verb
4.object complement
5.complement of the preposition
6. in apposition to a noun

(b). RELATIVE CLAUSE: Most relative clauses are introduced by relative pronoun like ‘who’,’which’,’that, ‘whom’ etc
 The function of a relative clause is the same as that of adjectival phrase, that qualifies a noun or pronoun preceding it. 

(c).ADVERBIAL CLAUSE: The adverbial clause is like the adverbial phrase. the adverbial clause performs the grammatical function of modifying the verb in the main Clause or sentence. consider the following,
adverbial clause are indicators of :
1.time (when, after, as soon as, before, whenever, while, since etc)
2 .place (where, wherever, etc)
3. condition ( unless, if, until, provided, etc)
4.manner ( as, if etc) 
5.reason and purpose ( because, in order that, so as, so that etc)
6.concession ( though,yet, although, etc)
7.results( that)
The function of an adverbial clause is so modifiy a verb in a sentence.