clog up vs silt

clog up is not a noun while silt is a noun.

Word	Noun	Adjective	Verb	Adverb
clog up	No	No	Yes	No
silt	Yes	No	Yes	No

As verbs, silt is a hyponym of clog up; that is, silt is a word with a more specific, narrower meaning than clog up:

Other hyponyms of clog up include gum up, block, choke up, lug, stuff, silt up.

clog up (noun)	silt (noun)
	mud or clay or small rocks deposited by a river or lake

clog up (verb)	silt (verb)
become or cause to become obstructed	become chocked with silt