knock-on effect vs effect

knock-on effect and effect both are nouns.

Word	Noun	Adjective	Verb	Adverb
knock-on effect	Yes	No	No	No
effect	Yes	No	Yes	No

As nouns, effect is a hypernym of knock-on effect; that is, effect is a word with a broader meaning than knock-on effect:

Other hypernyms of knock-on effect include consequence, event, issue, outcome, result, upshot.

knock-on effect (noun)	effect (noun)
a secondary or incidental effect	an outward appearance
	(of a law) having legal validity
	an impression (especially one that is artificial or contrived)
	the central meaning or theme of a speech or literary work
	a phenomenon that follows and is caused by some previous phenomenon
	a symptom caused by an illness or a drug

knock-on effect (verb)	effect (verb)
	produce
	act so as to bring into existence