clog vs clog up

clog is a noun but clog up is not a noun.

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

As verbs, clog and clog up are synonyms defined as:

Other synonyms of clog include back up, choke, choke off, congest, crap up, foul.

clog (noun)	clog up (noun)
a dance performed while wearing shoes with wooden soles; has heavy stamping steps
any object that acts as a hindrance or obstruction
footwear usually with wooden soles

clog (verb)	clog up (verb)
impede with a clog or as if with a clog	become or cause to become obstructed
fill to excess so that function is impaired
coalesce or unite in a mass
become or cause to become obstructed
impede the motion of, as with a chain or a burden
dance a clog dance