The verb has a central role in the clause and it is rare to omit it from a clause.
The fish (subject) eats (verb) fish food (object) by the handful (adverbial).
We can remove the adverbial: The fish eats fish food.
The object: The fish eats by the handful.
The subject, in casual style: Eats fish food by the handful. (Pointing at the tank).
But we cannot omit the verb: The fish fish food by the handful.
However, there are such things as 'verbless' clauses, which I will look at later on.
Only one verb element is allowed per clause. Sometimes that will just be one verb:
John (subject) went (verb) home (adverbial).
Or multiple verbs working together to form one meaning:
John (subject) has gone (verb) home (adverbial).
Although 'has gone' is two verbs, they work together to express one thing, so they count as one verb element.
These are verbs that can be written without an object:
The builder's going.
Some common intransitive verbs are:
Verbs which require an object are traditionally known as transitive verbs. Enjoying is an example:
The builder's enjoying his lunch.
Some common transitive verbs are:
Some verbs can be used intransitively or transitively. For example:
She's expecting a reply. She's expecting.
He worked wonders. He worked.
As you can see from the example, what often happens is that the verb changes meaning when used in these different ways.